Door-Spring., patent, October 15, 1901; (https://texashistory.unt.edu/ark:/67531/metapth514267/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Door-Spring., patent, October 15, 1901; (https://texashistory.unt.edu/ark:/67531/metapth514267/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .