As noted in another thread, there is an issue with a Wizard of Oz uncredited cast listing. Doing some digging I found:

https://oz.fandom.com/wiki/The_Wizard_of_Oz_Minor_Cast_Members

At the bottom is a reference to a 1977 book, which I am guessing is where they got the list from. If that book isn't good enough, I don't know what is.

My local library has a copy of the book. I just tried to reserve it, but it seems my card has expired. I guess I gotta fix that before getting the book.