Rotary Boring-Drill, patent, January 13, 1920; (https://texashistory.unt.edu/ark:/67531/metapth1259487/m1/1/: accessed July 7, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Rotary Boring-Drill, patent, January 13, 1920; (https://texashistory.unt.edu/ark:/67531/metapth1259487/m1/1/: accessed July 7, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .