I've already brought this up here, a few months earlier, when you first posted about the book.
In The Two of Them, Russ explicitly references Wilhelm's novel. On page 142 of my Women's Press edition, Irene says to Ernst: "Give me the Clewiston Test when we get back to Center; see if I'm mad."
Anne Clewiston, the title character and protagonist of Kate Wilhelm's novel, published a few years before Russ's, is a scientist whose sanity is put into doubt by her husband, during a period where she's forced to be dependent on him (while she's recoving from severe injuries). It's *really* really interesting to see the dialogue between the two books. They both describe the collapse of a partnership between a woman and a man, when she finds out that she can't trust him, but in very different ways. And the whole theme of captivity and insanity, for the animal test subjects in Wilhelm's book, and Aunt Dunya in Russ's book. And the political dynamics at work when captors ascribe insanity to captives.
You really should take a look at that book.
Thank you for the recommendation. At least it would probably make some interesting context for the Russ book. (I'm not able to put it on the class list both because I'm sharply limited in the number of full-length books I can put on syllabus and also because it looks to be out-of-print; the only reason I didn't use The Female Man instead of The Two of Them is that it really didn't as though my students would be reliably able to get hold of a copy).
At least it would probably make some interesting context for the Russ book.
It's a shame that it's out of print. I don't even have a copy of The Clewiston Test myself -- I'd read one I borrowed via an inter-library loan. If you can find a copy, maybe you could hand out a paragraph or two to your students. Perhaps from Anne's husband's point-of-view, to a comparison to Ernst's point of view. I'm sorry I can't give you any quotes from it.
Another intertextual connection would be the Suzette Haden Elgin short story "For the Sake of Grace" whose premise Russ borrowed for her novel -- I haven't had a chance to read it, though, because it's even harder to find.
But I'm rather happy for The Two of Them to have been your choice, if only by default, because it makes a change from the singular focus on The Female Man that usually leaves the rest of her work in shadow. (ObHow To Suppress Women's Writing...)