[Letter from Harris L. Kempner to Mr. Charles B. Barnes, Jr., April 11, 1957], letter, April 11, 1957; (https://texashistory.unt.edu/ark:/67531/metapth1419426/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .