'The Wizard of Oz: Parable on Populism' an important article first publish in the American Quarterly in 1964, by Hank Littlefield. It was the first work to document the links between L. Frank Baum's The wonderful wizard of Oz and the Populist Movement. While Littlefield later backed off his stance on the subject over the years, it is a widely taught theory among college level U.S. history courses.