Author Betty Friedan, frequently credited with laying the groundwork for modern feminism with her book, The Feminine Mystique, died of congestive heart failure Saturday. It was her 85th birthday.

Friedan was born in Peoria, Illinois on 4 February 1921. She studied psychology and worked as a journalist, but was primarily a housewife when she published her groundbreaking book in 1963.

The book's theme was that society forced women to find their identity through their husbands and children and allowed them little personal autonomy, leaving them unfulfilled. "The Feminine Mystique" was an immediate best-seller and made Friedan one of the most prominent voices in the women's movement of the 1960's and 70s.

She co-founded the National Organization for Women in 1966 and the National Political Women's Caucus in 1971.

Friedan's later work concentrated on how society views aging.

Some information for this report was provided by AFP, AP and Reuters.