[Letter from Harry T. Riddell to Bureau of Investigation Director John Edgar Hoover - 10/16/1933], legal document, October 16, 1933; (https://texashistory.unt.edu/ark:/67531/metapth78968/m1/1/: accessed May 4, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .