By: Lueptow, Lloyd B., Garovich-Szabo, Lori, and Margaret B. Lueptow.
These researchers review past research on sex typing between the years 1974 and 1997, finding that sex typing has remained constant during this period despite increased social pressure to minimize gender differences. They conclude that the research supports a theory of constant gender differences and discounts theories of gender roles stemming from socialization.
Social change and the persistence of sex typing: 1974-1997. Social Forces (1): 1-36.