[The Bell YH-40 in flight], photograph, May 2, 1958; (https://texashistory.unt.edu/ark:/67531/metadc949932/m1/1/: accessed April 20, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .
[The Bell YH-40 in flight], photograph, May 2, 1958; (https://texashistory.unt.edu/ark:/67531/metadc949932/m1/1/: accessed April 20, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .