My high school library had a book about the making of 2001: A Space Odyssey. I could only read it while I was in the library because I was severely overdue on a book... which just happened to be 2061: Odyssey Three. It had a lot of great photographs from the production of that film, but I'm not sure this one was one of them:
I am sure, however, that the book had a dead-on close-up of the zero gravity bathroom instructions seen here:
I can't find the same photo used in the book, but I did find this at PodSix.com in case you want to see them in detail, too.