The Wizard of Oz as an extended allegory for bimetallism was a theory proposed by Littlefield in the 60s, and it's been pretty much thoroughly debunked by literary scholars who point out that the characters are essentially common character tropes from 1890s literature, and biographers who pointed out that it's completely contrary to the views that Baum himself held.
Well then I suggest you take a trip to Wikipedia and start editing. For that current bit of trivia there are no less than 4 citations, three of which are from this century.
