Behnken, J. W. [Letter from J. W. Behnken to R. Osthoff, May 26, 1927], letter, May 26, 1927; (https://texashistory.unt.edu/ark:/67531/metapth606519/m1/1/: accessed April 23, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .