Hergens, J. B. [Letter from J. B. Hergens to Mr. D. W. Kempner, May 17, 1956], letter, May 17, 1956; (https://texashistory.unt.edu/ark:/67531/metapth1360933/m1/1/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .