My major primary sources were LeGuin's Left Hand of Darkness, Piercy's Woman on the Edge of Time and Butler's Xenogenesis series, though I had to discuss Atwood's Handmaid's Tale quite a bit because it was the book of the moment (though far more dystopian than any of the others). Also inevitable comparisons to Jean Auel, Suzy McKee Charnas, Linda Lay Shuler, Suzette Hayden Elgin, Gerde Brantenberg, Joanna Russ, Pamela Sargent, Sheri S. Tepper, and a whole bunch of others. I had not discovered Nancy Kress at the time which is a pity -- I'd love to write an academic paper on her!

If you're looking for critical sources, I would be happy to send you my bibliography, but it's ten years outdated...