The Female Man by Joanna Russ

Living in an altered past that never saw the end of the Great Depression, Jeannine, a librarian, is waiting to be married. Joanna lives in a different version of reality: she's a 1970s feminist trying to succeed in a man's world. Janet is from Whileaway, a utopian earth where only women exist. And Jael is a warrior with steel teeth and catlike retractable claws, from an earth with separate-and warring-female and male societies. When these four women meet, the results are startling, outrageous, and subversive.