Henderson, Roy E. [Letter from Roy E. Henderson to H. L. Williams, October 12, 1973], letter, October 12, 1973; (https://texashistory.unt.edu/ark:/67531/metapth1211592/m1/1/: accessed August 15, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .