Butzel, Henry M. [Letter from Henry M. Butzel to I. H. Kempner, November 20, 1957], letter, November 20, 1957; (https://texashistory.unt.edu/ark:/67531/metapth1512798/m1/1/: accessed July 9, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .