Shadowgraph., patent, April 16, 1918; (https://texashistory.unt.edu/ark:/67531/metapth1259497/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .
Shadowgraph., patent, April 16, 1918; (https://texashistory.unt.edu/ark:/67531/metapth1259497/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .