1. http://www.ilife99.com/?p=3798#.VoCdLFkVHqA 

2. https://ed.ted.com/lessons/does-the-wonderful-wizard-of-oz-have-a-hidden-message-david-b-parker

In his introduction to “The Wonderful Wizard of Oz,” L. Frank Baum claims that the book is simply an innocent children’s story. But some scholars have found hidden criticisms of late-nineteenth-century economic policies in the book. Is it possible that one of America’s favorite children’s stories is also a subversive parable? David B. Parker investigates the text for clues.