Apparatus for Stamping Envelopes, patent, September 24, 1889; (https://texashistory.unt.edu/ark:/67531/metapth172167/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .
Apparatus for Stamping Envelopes, patent, September 24, 1889; (https://texashistory.unt.edu/ark:/67531/metapth172167/m1/1/: accessed June 19, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .