Maddox, J. David. [Letter from J. David Maddox to John J. Herrera - 1973-02-12], letter, February 12, 1973; (https://texashistory.unt.edu/ark:/67531/metapth249764/m1/1/: accessed April 23, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .