The Hungry Tiger of Oz gives Betsy Bobbin another chance as a leading character in an Oz story. Betsy was basically a Dorothy substitute in Tik-Tok of Oz, and tends to simply get lumped along with the other American girls in Oz.
In this book from 1926, Ruth Plumly Thompson used Betsy in a starring role, along with the Hungry Tiger. I feel the Tiger also received minimal attention in other tales - but then, he is rather similar to the Cowardly Lion. One of the nice things about the number of Oz books written, is that almost every character eventually gets a chance to lead a story!
I believe most of the drawings for the color plates in this book survive. From what I can tell, there isn't much rhyme or reason to what does and doesn't exist in terms of Oz artwork.