Haha yeah, that's just classic, really. Chances are good that a similar thing would happen to me if I ever did manage to find Andreev's paper. Maddening.

Oh! I just remembered another fun one! I once ran across a theorem which according to the paper I found it in was proven in this other paper. So I go to the other paper, and they say "your proof is in another castle (paper)", so I find that one, and it's in german, shittily typed on a typewriter, with the most arcane notation I've ever seen. So what do I do? You guessed it! I just cite the first paper where I found the theorem, which isn't great, because now anyone who reads my dissertation gets to go down exactly the same rabbit hole! Neat!