[Letter from Isaac Herbert Kempner to Gus A. Stirl, June 28, 1960], letter, June 28, 1960; (https://texashistory.unt.edu/ark:/67531/metapth1198251/m1/1/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .