Educational Souvenir., patent, February 2, 1915; (https://texashistory.unt.edu/ark:/67531/metapth858805/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Educational Souvenir., patent, February 2, 1915; (https://texashistory.unt.edu/ark:/67531/metapth858805/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .