American author Nancy Friday, who wrote on gender and women’s sexuality, died on Sunday in her New York apartment, The New York Times reported. She was 84 and was suffering from Alzheimer’s.

Her first book, My Secret Garden: Women’s Sexual Fantasies, published in 1973, is considered a seminal book in the expression of the female sexual fantasy. The bestseller is a compilation based on letters and interviews exchanged with several women. It was also adapted for stage in 2007.

Her books on gender politics “helped redefine American women’s sexuality and social identity” in the late 20th century, according to The New York Times.

Other books by Friday include Forbidden Flowers: More Women’s Sexual Fantasies (1975), My Mother/My Self: The Daughter’s Search for Identity (1977), Jealousy (1985), The Power of Beauty (1996) and Lulu: A Novella (2012).