Since there's been interest in the past in finding parallels between Wolfe's works and the Oz books, I thought I'd pass along this tidbit from Wolfe's essay in Contemporary Authors Autobiography Series vol. 9: discussing his childhood reading in Houston, Wolfe writes "I mixed them with Oz books--the best were by Ruth Plumly Thompson." (301) He doesn't say explicitly that he prefers Thompson to Baum (there were several writers of Oz books after Baum's death), but it's hard to imagine that he wouldn't have read any Baum.
--Adam