Penrose, Neville G. [Letter from Neville G. Penrose to Alfred J. Hernandez - 1966-06-23], letter, June 23, 1966; (https://texashistory.unt.edu/ark:/67531/metapth250850/m1/1/: accessed July 8, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .