There is no single brain switch that decides whether we are male or female, but probably separate levers controlling degrees of maleness and femaleness in different aspects of sex-role behavior. Mentions several important brain areas such as the hypothalamus. (Wilson, Glenn. The Great Sex Divide. England: Peter Owen Publishers, 1989, pp 35-36)

In the brain, gender is less plastic that other aspects of brain a large part we are hard wired to be who we are in terms of gender. After the first trimester of pregnancy, are sense of who we are (maleness or femaleness) is cemented into the brain. (Gurian, Michael, PhD., and Barbra Annis. Leadership and the Sexes. NY: Jossey-Bass, 2007. p 12, 23, 27)

Provides in list format information on brain gender differences (e.g., the part of the brain, function, similarities and differences, and impact). Excellent summary. (Gurian, Michael, PhD, and Patricia Henley, with Terry Trueman. Boys and Girls Learn Differently! CA: Jossey-Bass, 2001. p 20-26)