Drilling Apparatus, patent, April 29, 1919; (https://texashistory.unt.edu/ark:/67531/metapth1257344/m1/2/: accessed July 8, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Drilling Apparatus, patent, April 29, 1919; (https://texashistory.unt.edu/ark:/67531/metapth1257344/m1/2/: accessed July 8, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .