I am writing a paper right now, and part of the paper makes use of a (trivial) generalization of a number of really nice theorems and constructions from a paper that was never made public. The author has left pure mathematics and has no intention of publishing the paper, but I received a copy directly from him several years ago.

The results and constructions are crucial to my paper, and since I am working with a minor generalization, I think I do need to include the proofs, especially since they aren't available. I don't want it to look like I'm taking credit for the results or plagiarizing, but some of the proofs are basically copies. I have a bunch of disclaimers at the top of the section and continually remind the reader that all of these results are in the original paper.

Do I need to not only give credit at the top of the section, but also give credit for every observation, statement, lemma, and diagram?

PS It seems like the community wiki checkbox is gone. I'd appreciate if a moderator could do that for me.

Edit: I contacted the author, and he agreed to put it on the arXiv himself. Going to leave the question up as a community wiki for anyone else who runs into this problem.