The decision of gay and lesbian couples to raise families is
part of the high-profile political, legal, and religious debate over gay rights
in America. When it comes to the outcomes of their children, however, there is
little debate among the scientists who have studied them.
Studies conducted over more than
three decades are remarkably consistent in reporting that the sexual
orientation of parents does not harm the development of children raised in
same-sex families. And the vast majority of studies published to date report no
significant differences in gender development, personal development, and social
relationships among children of same-sex couples and children raised in
"Just like the research, what we’ve
seen in terms of development, children being cared for, and children being
happy suggests there isn’t any difference," said Betty Hill, executive director
of Persad Center, a Pittsburgh counseling center established in 1972 to provide
services to the gay, lesbian, bisexual, and transgender (GLBT) community. “I
can’t think of a case where a family has come in because their child is not
adjusting to having gay parents or is having develop-mental issues.”
That is not to say there is
complete agreement among researchers who study same-sex parents and their families.
Some say the data show certain differences do exist, although the differences
identified are not necessarily harmful to a child’s development. For example,
data in one study suggest older children raised by same-sex parents are more
open to the idea of same-sex relationships than children of heterosexual
parents. Questions about research methodology have also been raised,
particularly in regard to early studies of children in same-sex families.
However, organizations such as the
American Psychiatric Association, American Academy of Pediatrics, American
Psychological Association, and the Child Welfare League of America have found
the evidence that children raised by same-sex parents fare as well as children
whose parents are heterosexual to be strong enough to warrant their support.
“Research has shown that the adjustment, development, and psychological
well-being of children is unrelated to parental sexual orientation and that the
children of lesbian and gay parents are as likely as those of heterosexual
parents to flourish,” reads a portion of a 2004 American Psychological
Association resolution supporting joint adoptions and second-parent adoptions
of children raised by same-sex couples, and denouncing sexual orientation-based
discrimination in such matters.
Differences do exist in family law
and policies. The majority of states prohibit same-sex marriage and civil
unions. Most states deny legal recognition to same-sex couples legally married
in another state. And the ability of same-sex parents to adopt children varies
across jurisdictions throughout the United States.
Same-Sex Couples in
the United States
Efforts to determine the number of same-sex couples across
the United States have proven to be difficult and imprecise, yielding only
estimates of GLBT populations.
Most estimates are based on U.S.
Census Bureau data, often the 2000 census. Such estimates are widely considered
to be undercounts of the actual number of same-sex couples for several reasons.
One is the 1996 Defense of Marriage Act (DOMA), which complicated data
collection. The law required the Census Bureau to invalidate any responses that
designated a same-sex individual as a spouse. Those responses were assigned to
the same-sex unmarried-partner category.
Studies suggest that the Census
Bureau failed to account for as much as 19 percent of all same-sex couples in
the 2000 census.1 The census questionnaire, for example, did not ask the sexual orientation of the respondent. In the 2000
census, gay and lesbian households were determined by gender and relationship
only. The U.S. Census Bureau also did not count gays and lesbians who were in
relationships but not living together in the same residence.
Despite its limitations, the U.S.
Census Bureau data do offer a glimpse of America’s population of gay and
lesbian couples, which analyses suggest is increasing. Between 2000 and 2005,
for example, the estimated number of same-sex couples in the United States grew
nearly 30 percent, from 600,000 to almost 770,000, according to an analysis of
data from the American Community Survey, an ongoing statistical survey sent to
about 250,000 addresses each month by the U.S. Census Bureau.2
The same analysis, which was done
by The Williams Institute of the UCLA School of Law, found that the number of
same-sex couples increased 38 percent in Pennsylvania to more than 29,000
during the five-year period.
Using the 2000 census data sample,
Williams Institute re-searchers also estimated the number of same-sex couples
in each county in every state. In Pennsylvania, same-sex couples reside in all
67 counties. More than 4,300 same-sex couples were estimated to have resided in
Allegheny County in 20003—a number that is likely higher today given
the trends across Pennsylvania and the nation over the past decade.
Nationwide, same-sex couples
account for a very small percentage of households, ranging from .28 percent of
all households in South Dakota to 1.48 percent of all Washington, D.C.,
households. In Pennsylvania, same-sex couples ac-count for .67 percent of all
An estimated 39 percent of same-sex couples in the United
States between the ages of 22 and 55 were raising 250,000 children under 18
years of age at the time data were collected for the 2000 census.5
In Pennsylvania, more than 20 percent of the same-sex couples identified in the
2000 census reported they were raising children under age 18.6 In
Allegheny County, one measure of same-sex families with children is a 2002
survey conducted by University of Pittsburgh Graduate School of Public Health
researchers as part of a community assessment for Persad Center. In that
survey, 57 percent of the 910 respondents reported being in a couple
relationship, and more than 16 percent of those reported they were raising
Legal and Policy Issues
for Same-Sex Families
Same-sex families function in a legal and policy environment
much different than what most families with heterosexual parents encounter.
Only six states issue marriage licenses to same-sex couples. Over the years,
same-sex couples in the United States have encountered challenges related to
their custody of and visitation with children from a previous heterosexual
marriage. In some cases, they have also encountered limitations on opportunities
to adopt children or be-come foster parents.8
Such issues can affect same-sex
families in several ways, ranging from access to employer-based health
insurance to legal recognition of joint parenting rights when a child is born
Marriage and Civil Unions
Legal recognition of same-sex relationships remains an issue
of sharp controversy in America. The legal landscape affecting recognition of
these relationships is complex, rife with uncertainty, and varies across
jurisdictions. Although all states have laws that address the legal status of
same-sex relationships in some way, uncertainty lingers as debate over those
issues continues to arise in courts and legislatures across the nation. For
example, California state law permits same-sex marriage, but earlier this year,
a proposition on California ballots that sought to restrict marriage to only
heterosexual couples won voter approval. A U.S. District Court judge later
struck down the proposition, but that ruling is likely to be challenged in an
There are several different legal
definitions for relationships between couples. Civil marriage is a legal status
granted with a license from a state government. Religious marriage is
recognized by a religious group, based on its own rules about who may marry. In
the United States, state governments grant priests, rabbis, and other clergy
the authority of the state to endorse the license and establish a civil
A civil union is a legal act by a
government that can grant same-sex couples legal status similar to that offered
by civil marriage. Same-sex couples can also enter into domestic partnership
agreements, which can result in contracts related to issues such as property
and finance, but do not offer the level of legal recognition that civil
marriages and civil unions afford.
In the United States, the 1996
Defense of Marriage Act prohibits the federal government from legally
recognizing same-sex civil marriage. The law also allows states to enact
similar prohibitions, and all but six states have such prohibitions, including
At the time of this writing, only
Massachusetts, Connecticut, California, Iowa, Vermont, New Hampshire and the
District of Columbia have laws that allow the state to issue civil marriage licenses
to same-sex couples. While Rhode Island, New York, and Maryland do not issue
marriage licenses to same-sex couples, they do recognize same-sex marriages
from other states. Pennsylvania is among the majority of states that do not
recognize the legality of same-sex marriages granted in other jurisdictions.
New Jersey allows civil unions of
same-sex couples. Connecticut, Vermont, and New Hampshire, all of which had
previously allowed same-sex civil unions, have re-placed those statutes with
laws allowing same-sex civil marriages. Pennsylvania is among the majority of
states that do not grant same-sex civil unions and do not recognize civil
unions from other states.
Adoption laws vary considerably across states. State laws
address several adoption scenarios related to GLBT individuals and same-sex
couples. Those issues include whether single GLBT individuals are permitted to
adopt a child, whether a same-sex couple can adopt a child, and whether a
same-sex co-parent can adopt a partner’s child or a child of the relationship,
such as a child conceived through artificial insemination.
Many states permit some of these
adoption arrangements. In most cases, however, state law does not explicitly
permit or prohibit at least one of the kinds of adoption situations that apply
to GLBT individuals and same-sex couples, leaving it up to individual courts to
decide.9 State law in Pennsylvania, for example, allows GLBT
individuals to adopt and permits a same-sex co-parent to adopt a partner’s
child or a child of the relationship. However, the law is not explicit about
whether same-sex couples can or cannot jointly adopt a child.
In some states, the law itself may
not explicitly forbid same-sex couples from adopting, but specific provisions
effectively prohibit them from doing so. Adoption laws in Mississippi, Utah,
and Arkansas, for example, prohibit unmarried couples from adopting. In each of
those states, same-sex civil marriage is not granted or legally recognized.
For same-sex couples and their children, laws and policies
related to the legal recognition of their relationships, in particular, have an
impact on several important family issues.
Laws prohibiting civil marriage and
civil unions among same-sex couples jeopardize their ability to obtain many
le-gal and financial rights, benefits, and protections typically afforded
married heterosexual couples, including legal recognition of joint parenting
rights when a child is born or ad-opted, eligibility for public housing and
housing subsidies, access to employer-based health insurance for partners and
some children, access to Medicare and Medicaid spouse benefits, the ability to
make medical decisions for an incapacitated partner, visitation rights and
custody of children after a relationship is dissolved, Social Security survivor
benefits, and others.10
Other implications of such laws and
policy are less apparent. For example, one Pittsburgh same-sex couple identified
the process of adopting their three children as the most stressful moments in
their life as a couple and family.
Holly Hippensteel and Cheryl Dennis
decided to have children based on their long-held desire to raise a family.
They have been a couple for 16 years. Today, their family includes an
8-year-old son, Spencer, and two daughters, Hanna, 5, and Madalyn, 2.
Dennis had the children through
donor insemination. Hippensteel had to arrange a co-parent adoption to become a
legally recognized parent of each of the children. “That was stressful,” said
Dennis. “A social worker had to come in and do a home visit, just as if we were
adopting a stranger’s child. I was like, what is this all about? Are they going
to allow Holly to adopt them?”
During their first court
experience—Hippensteel’s adoption of their son—the judge asked why the couple
was not married, even though Pennsylvania does not legally grant or recognize
same-sex marriage. The couple had arranged to have a large number of friends
and relatives attend the proceeding as part of the court’s requirement of proof
they had an established relationship. But none of their witnesses were called
to testify. Later, when Hippensteel adopted their two daughters, they asked
friends and family to submit their testimony in letters, rather than attend and
not be called. The judge in that case, however, questioned why few family and
friends were in attendance and expressed concern that the couple hadn’t
organized a “bigger celebration” of the adoption.
“That whole process, for me, was
stressful,” said Hippensteel. “I felt it was very judgmental. I felt very
vulnerable, that it was possible that it might not go our way. We really didn’t
know. I felt as if our relationship was on trial.”
Children of Same-Sex Parents
One of the central issues in the debate over legal rights
and policies related to same-sex parents is the well-being of children raised
in those families. The body of research con-ducted over more than three decades
provides insight into a range of issues, including the personal development,
gender development, peer relationships, and family relationships of children
with same-sex parents.
Studies suggest, for example, that
children’s development is influenced more by the nature of the relationships
and interactions within the family than by the sexual orientation of their parents.11
Overall, studies that have looked specifically at children raised by GLBT
parents report that their development is not harmed by having same-sex parents,
and most have found no significant developmental differences between those
children and children raised by hetero- sexual parents.
Research suggests that children of same-sex parents, in general,
have typical relationships with their peers in their neighborhoods and at
school, with family members, and with adults outside the family. For example,
studies that have examined relationships between children of same-sex parents
and members of their families report that those relationships do not differ
significantly from relationships found among children with heterosexual parents
and their family members.12
Some studies do report finding that
a minority of children with lesbian mothers report having been teased or having
heard negative comments from peers. Research suggests, however, that such
anecdotal evidence does not appear to represent a broadly experienced problem
of such a degree that it affects the overall adjustment and peer relationships
of children with same-sex parents. For example, a recent study found that
differences in peer relationships across a national sample of adolescents were
not related to whether adolescents were raised by same-sex parents or
Social relationships were among the
issues Doris Dick and Sharon Geibel considered when they adopted their son,
Dylan, 5, in 2008. The two parents entered into a civil union in New Jersey,
where Dick was raised and where such arrangements are legal. They adopted Dylan
after falling in love with him as his foster parents.
They had several concerns. “We
didn’t know for sure how children interact with children who are adopted. You
have a sense of that, but until you live it you never really know. So we
thought, that’s one thing,” said Geibel. “Another thing was, are people going
to torment this child because he has two moms? You never want a child to experience
pain. When the very beginning of his life was folded into pain, the desire to
not have him experience any more pain is very real. It wasn’t a stumbling block,
but it gave me pause. It wasn’t a question of whether or not we could do it,
but whether it would be one more thing that people would be mean to him about.”
However, family members on both
sides have accepted their son and do not treat him differently than other
nieces, nephews, and grandchildren, said Dick and Geibel. So far, social
relationships have not been a problem at home or in preschool. Their son, for
example, has three friends in their neighborhood who are about his age. “They
embrace him and us,” said Dick. “I’ve never felt he is being treated
differently. He’s only five. Things may become harder when he’s older. But so
far there’s been nothing overt.”
Researchers have studied a range of characteristics among
children of same-sex families, including separation-individuation, behavior
problems and competencies, self-concept, moral judgment, adjustment to school,
intelligence, and drug and alcohol use.14 Two other studies that
looked at adjustment among adolescents, for example, found no significant
differences between those living with lesbian couples and those raised by
heterosexual parents on measures of anxiety, depressive symptoms, self-esteem,
delinquency, victimization, or use of tobacco, alcohol, or marijuana.15,
16 Overall, studies of such aspects of personal development re-port no
significant differences between children in same-sex families and those raised
by heterosexual parents.
For Dick and Geibel, their son’s
development and adjustment is complicated by the fact he was born prematurely
and had spent several years in foster care, during which time he had been
separated from his biological mother. He has exhibited some developmental
delays. Adoption, however, has provided him with stability and he has shown
steady improvement in his development, the couple said. “When we adopted Dylan,
the whole structure of our day, of our lives, was changed,” said Geibel, who
reduced her hours at work to be home when he returns from school. “Everything
is structured around what’s going to help him thrive.”
Attachment is one of the issues
that has improved. “He feels loved and secure,” Dick said. “That wasn’t the
case initially. He wouldn’t come and greet us when we picked him up at school.
He was always protecting himself. It was a risk for him. He had attached before
and it was ripped away—people he loved would go away, so he wasn’t going to do
it that easily. So, when he’d yell mommy and run and jump in our arms, we knew
we bonded and he was attached.”
The question of whether gender development is compromised
among children who are raised by same sex parents has at times been raised in
the debate over gay and lesbian rights regarding families, marriage, and civil
Research, in general, has found no
significant differences in the development of gender identity or gender role
behavior related to the sexual orientation of a child’s parents. For example,
one study reported finding no significant differences in the selection of
favorite toys, television programs, television characters, and games among
children with divorced lesbian mothers and children with divorced heterosexual
A study involving children
conceived through artificial insemination reported no significant differences
between children raised by lesbian couples and children raised by heterosexual
couples in terms of their preferences of games, toys, and activities as
measured by parent responses to the Preschool Activities Inventory.18
Another study that examined data obtained with the Preschool Activities
Inventory found no significant differences in the gender role behavior of young
children adopted by lesbian, gay, and heterosexual couples.19
Dennis and Hippensteel said they
made an effort not to influence their children’s preferences for such things as
games, toys, and activities. “With Spencer we felt we would take our cues from
him about what he’s interested in,” Hippensteel said. “I wasn’t going to try to
shove things down his throat that were boy things. We would just see. Early on
he was completely fascinated with anything that moved—trains, planes, cars,
trucks, everything with wheels and engines. He was really drawn to all of that
stuff. With Hanna, it’s pink everything.”
Overall, the research suggests that
the majority of children raised by GLBT couples grow up to identify themselves
as heterosexual.20 In one study, for example, 91 percent of the sons
of the 75 gay fathers studied identified themselves as heterosexual.21
In another study, none of the adolescents raised by lesbian mothers who were
interviewed by researchers identified themselves as non-heterosexual.22
In 2001, University of Southern California researchers
published, “(How) Does the sexual orientation of parents matter?” The study
identified several methodological shortcomings among studies related to
same-sex families, and cautioned against making global statements that suggest
no insightful differences have been found between children raised by same-sex
parents and those raised by heterosexual parents.
The study examined 21 studies
related to children raised in same-sex families. It noted the difficulties in
obtaining representative samples of children and parents. The studies tended to
involve more lesbian mothers and their children than gay fathers and their
children, and GLBT data tend to be drawn from families of comparatively
well-educated white lesbian couples who live in progressive urban areas.
The researchers also noted several
differences found be-tween children of same-sex parents and heterosexual
parents, although these were not necessarily deficits.
In one study, for example, researchers
who looked at the sexual identities of young adults who had been raised by divorced
lesbian and divorced heterosexual mothers reported no differences between the
two groups.23 However, data from that study showed a significant
difference in the openness of the two groups of young adults to the idea of
having a same-sex relationship: 64 percent of the young adults raised by lesbian
mothers reported having considered same-sex relation-ships compared with 17
percent of those who were raised by heterosexual mothers.
Another area of difference found in
the studies was in stereotypical male-female behavior. The researchers, for
example, found evidence of such differences in behavior in a study that
reported that preferences for toys, games, television programs, and other
activities were not significantly different among children of divorced lesbian
mothers and children of divorced heterosexual mothers. But that study also
found that 53 percent of the daughters of lesbian mothers aspired to pursue
careers as physicians, attorneys, and engineers compared with only 21 percent
of the daughters of heterosexual mothers.24 The sons of lesbian
mothers also tended to be less aggressive and more nurturing than the sons of
In 2010, Pediatrics published a study that followed 78 children
of lesbian mothers from birth to adolescence. The study focused on planned
lesbian families “ families in which mothers had identified themselves as
lesbian at the time of artificial insemination.
The study concluded that
adolescents who were raised in the lesbian mother families since birth showed
healthy psychological adjustment. The data were gathered through inter-views
and questionnaires completed by the children at ages 10 years and 17 years, and
through interviews with mothers conducted at the same times. The mothers also
completed the Achenbach Child Behavior Checklist, a widely-used method of
identifying behavior issues in children. Those responses were compared with an
Achenbach normative sample of 17-year-old U.S. adolescents.
The children of lesbian mothers
were found to have lower levels of social problems, rule-breaking, aggression,
and externalizing problems than the normative adolescent sample. Among the
possible explanations for such outcomes suggested by the researchers were the
widespread use among lesbian mothers in the study of child-rearing practices
such as verbal limit-setting, and less
reliance on corporal punishment and power assertion in their parenting.
Children of the lesbian mothers
also demonstrated higher levels of social, academic, and total competence than
the gen-der-matched normative samples of American adolescents. The researchers
suggested these outcomes were related to the high proportion of lesbian mothers
in the study who were fully engaged in parenting. During pregnancy, for
example, lesbian mothers took classes and formed support groups to earn more
about raising children. They were also actively involved in the children’s
Such findings suggest the desires
of same-sex parents are not unlike those of heterosexual parents. “When
children come along, I think many people’s family lives are pretty much like
everybody else’s,” said Persad Center Executive Director Betty Hill. “At some
point, your life sort of centers around what your children are involved in. You
are going to the softball games and sitting on the same bleachers with everyone
else.” Hippensteel and Dennis said their goal is to establish normalcy in their
family life. “We want to have what I think most parents want to have—happy,
healthy kids, a good relationship, work, to feel fulfilled, and to enjoy life,”
Hippensteel said. “I joke with people at work that if you describe us without
our names or genders we sound very much like Ozzie and Harriet: I work full
time. Cheryl stays at home. We have three kids and two dogs.”
Patterson, C.J. (2009). Children of lesbian and gay parents:
Psychology, law, and policy. American Psychologist, 727-736.
Gartrell, N., & Bos, H. (2010). U.S. longitudinal
lesbian family study: Psychological adjustment of 17-year-old adolescents.
Pediatrics, 126 (1),
Stacey, J., & Biblartz, T.J. (2001). (How) Does the
sexual orientation of parents matter? American Sociological Review, 66 (2),
This Special Report is based on interviews, the publications
cit-ed above, and the following references noted in the text. It is not intended to be an original work,
but a summary of the research for the convenience of our readers.
1 Badgett, M.V.L,
& Rogers, M.A. (2003). Left Out of the Count: Missing Same-Sex Couples in
Census 2000: Amherst, MA: Institute for Gay and Lesbian Strategic Studies.
2 Gates, G.J. (2006).
Same-sex Couples and the Gay, Lesbian, Bi-sexual Population: New Estimates from
the American Community Survey. Los Angeles, CA: The Williams Institute on
Sexual Orientation Law and Public Policy, UCLA School of Law.
3 Romero, A., Baumle,
A., Badget, M.V.L., & Gates, G. (2007). Census Snapshot: Pennsylvania
December 2007. Los Angeles, CA: The Williams Institute on Sexual Orientation
Law and Public Policy, UCLA School of Law. http://law.ucla.edu/williamsin-stitute/publications/PennsylvaniaCensusSnapshot.pdf
4 Sears, R.B., Gates,
G., & Rubenstein, W.B. (2005). Same-Sex Couples and Same-Sex Couples
Raising Children in the United States: Data from Census 2000. Los Angeles,
Calif.: The Williams Project on Sexual Orientation Law and Public Policy, UCLA
School of Law.
6 Romero, Baumle,
Badget, & Gates, op. cit.
7 Crouse Quinn, S.,
Aaron, D., Schwarz, K., & Thomas, T. (2003). Voices for a New Tomorrow: An
Assessment of the Lesbian, Gay, Bisexual and Transgender Community of Allegheny
County. Pittsburgh, PA: Persad Center, Inc.
8 Joslin, C.G., &
Minter, S.P. (2008). Lesbian, Gay, Bisexual and Transgender Family Law. New
York: Thomson West.
9 Human Rights
Campaign (2010). Adoption Laws: State by State. Washington, DC: Human Rights
Campaign Foundation. http://www.hrc.org/issues/parenting/adoptions/8464.htm
10 Pawelski, J.G.,
Perrin, E.C., Foy, J.M., Allen, C.E., Crawford, J.E., Del Monte, M., Kaufman,
M., Klein, J.D., Smith, K., Springer, S., Tanner, J.L., & Vickers, D.L.
(2006). The effects of marriage, civil union, and domestic partnership laws on
the health and well-being of children. Pediatrics, 118 (8); 349-364. www.pediatrics.aappublications.org/cgi/content/full/118/1/349
11 Perrin, E.C.
(2002). Technical report: Coparent or second-parent adoption by by same-sex
parents. Pediatrics, 109(2), 341-344.
12 Fulcher, M, Chan,
R.W., Raboy, B., & Patterson, C.J. (2002). Contact with grandparents among
children conceived via donor insemination by lesbian and heterosexual mothers.
Parenting: Science and Practice, 2, 61-76.
13 Wainwright, J.L.,
& Patterson, C.J. (2008). Peer relations among adolescents with female same-sex
parents. Developmental Psychology, 44, 117-126.
14 Patterson, C.J.
(2006). Children of lesbian and gay parents. Current Directions in
Psychological Science, 15, 241-244.
15 Wainwright, J.L.,
& Patterson, C.J. (2006). Delinquency, victimization, and substance use
among adolescents with female same-sex parents. Journal of Family Psychology,
16 Wainwright, J.L.,
Russell, S.T., & Patterson, C.J. (2004). Psychological adjustment and
school outcomes of adolescents with same-sex parents. Child Development, 75,
17 Green, R., Mandel,
J.B., Hotvedt, M.E., Gray, J., & Smith, L. (1986). Lesbian mothers and
their children: A comparison with solo parent heterosexual mothers and their
children. Archives of Sexual Behavior, 15, 167-184.
18 Brewaeys, A.,
Ponjaert, I., Van Hall, E.V., & Golombok, S. (1997). Donor insemination:
Child development and family functioning in lesbian mother families. Human
Reproduction, 12, 1349-1359.
19 Patterson, C.J.,
Farr, R.H., & Forssell, S.L. (2009). Sexual orientation, parenting, and
child development in adoptive families. Paper presented at the biennial meeting
of the Society for Re-search in Child Development, Denver, Colorado.
20 Bailey, J.M.,
& Dawood, K. (1998). Behavior genetics, sexual orientation, and the family.
In C.J. Patterson & A.R. D'Augelli (Eds.), Lesbian, gay and bisexual
identities in families: Psychological perspectives. New York: Oxford
21 Bailey, J.M.,
Bobrow, D., Wolfe, M., & Mikach, S. (1995). Sexual orientation of adult
sons of gay fathers. Developmental Psychology, 31, 124-129.
22 Huggin, S.L.
(1989). A comparative study of self-esteem of adolescent children of divorced
lesbian mothers and divorced heterosexual mothers. In F.W. Bozett (Ed.),
Homosexuality and the Family. New York: Harrington Park Press.
23 Tasker, F.L.,
& Golombok, S. (1997). Growing up in a lesbian family: Effects on child
development. New York: Guilford Press.
24 Green, Mandel,
Hotvedt, Gray, Smith, op. cit.