Hagen, William. [Letter from William Hagen to the Reverend R. Osthoff, July 26, 1928], letter, July 26, 1928; (https://texashistory.unt.edu/ark:/67531/metapth606398/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .