Bonus points (BPs) for when you get entire sentences full of abbreviations (SFOA). Even more BPs when you get SFOA with abbreviations containing abbreviations within them (SWACAWT). I really hate SWACAWTs.
I call BS, there's not enough room for this sort of detail, you'd get 'as described previously in [1-4, 9, 84, 86, 150-160, unpublished observations]' half of which are unaccessible journals, out of print book chapters, and abstracts in German
I only encountered once, but when it happened I had to realize how old science field may have been different.
The exact detail I was looking for should be in [20] ... but "[20] to be published" (presumably by the same author). I couldn't find any papers by author's name other than that but the author was so sure getting published.
My favorite is recursive bad citations in the method section. As in, citing a paper that cited a previous paper that itself cited a previous paper that cited an abstract with no detailed methodology whatsoever, leaving the true methods a mystery unless you get the senior author to reply to emails.