Drill-Bit, patent, June 4, 1918; (https://texashistory.unt.edu/ark:/67531/metapth1256805/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Drill-Bit, patent, June 4, 1918; (https://texashistory.unt.edu/ark:/67531/metapth1256805/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .