[Closeup of the rotor of YH-40 #2], photograph, March 19, 1958; (https://texashistory.unt.edu/ark:/67531/metadc950121/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .
[Closeup of the rotor of YH-40 #2], photograph, March 19, 1958; (https://texashistory.unt.edu/ark:/67531/metadc950121/m1/1/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .