O. P. Jackson Seed Company, Incorporated. [Letter from O. P. Jackson Seed Co., Inc. to D. W. Kempner, May 18, 1961], letter, May 18, 1951; (https://texashistory.unt.edu/ark:/67531/metapth1372060/m1/1/: accessed July 6, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .