^Sexual Orientation and Gender Expression in Social Work Practice, edited by Deana F. Morrow and Lori Messinger (2006, ISBN0231501862), p. 8: "Gender identity refers to an individual's personal sense of identity as masculine or feminine, or some combination thereof."
^V. M. Moghadam, Patriarchy and the politics of gender in modernising societies, in International Sociology, 1992: "All societies have gender systems."
^Jack David Eller, Culture and Diversity in the United States (2015, ISBN1317575784), p. 137: "most Western societies, including the United States, traditionally operate with a binary notion of sex/gender"
^For example, "transvestites [who do not identify with the dress assigned to their sex] existed in almost all societies." (G. O. MacKenzie, Transgender Nation (1994, ISBN0879725966), p. 43.) "There are records of males and females crossing over throughout history and in virtually every culture. It is simply a naturally occurring part of all societies." (Charles Zastrow, Introduction to Social Work and Social Welfare: Empowering People (2013, ISBN128554580X), p. 234, quoting the North Alabama Gender Center.)