Route-Indicator., patent, November 13, 1917; (https://texashistory.unt.edu/ark:/67531/metapth854045/m1/1/: accessed June 20, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .
Route-Indicator., patent, November 13, 1917; (https://texashistory.unt.edu/ark:/67531/metapth854045/m1/1/: accessed June 20, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu.; .