Spring-Tooth Harrow, patent, June 2, 1908; (https://texashistory.unt.edu/ark:/67531/metapth508855/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Spring-Tooth Harrow, patent, June 2, 1908; (https://texashistory.unt.edu/ark:/67531/metapth508855/m1/1/: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .