Extension-Ladder., patent, November 3, 1891; (https://texashistory.unt.edu/ark:/67531/metapth172836/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Extension-Ladder., patent, November 3, 1891; (https://texashistory.unt.edu/ark:/67531/metapth172836/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .