Mehan, R. I. [Letter from R. I. Mehan to Mrs. N. Hartung, March 4, 1957], letter, March 4, 1957; (https://texashistory.unt.edu/ark:/67531/metapth1476850/m1/1/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .