[Letters from Peter Enriquez and Manual Urbina to Esteban Flores and D. E. Sloan - 1966-08-02], letter, August 2, 1966; (https://texashistory.unt.edu/ark:/67531/metapth221947/m1/1/: accessed May 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .