Pitman - Coupling., patent, March 15, 1898; (https://texashistory.unt.edu/ark:/67531/metapth510212/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Pitman - Coupling., patent, March 15, 1898; (https://texashistory.unt.edu/ark:/67531/metapth510212/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .