I once wrote a paper related to genetics. It's known that cells contain various parts (organelles), some of which used to be independent cells. Those are rather well researched but finding scientific references for some points were surprisingly difficult and I had to quote some 1940s papers to actually have a solid citation for a well-known but not trivially verifiable fact.

I can imagine much common knowledge is difficult to proof and the various alternate Nobel prizes are great at rewarding some of this important but hardly recognised work of "proving the obvious".