Cooper, Reggie. [Letter from Reggie Cooper to Gertrude C. Macomber, April 2, 1964], letter, April 2, 1964; (https://texashistory.unt.edu/ark:/67531/metapth1420998/m1/1/: accessed July 9, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .