[The Bell 412SP on the ground], photograph, February 1990; (https://texashistory.unt.edu/ark:/67531/metadc950060/m1/1/: accessed May 11, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .
[The Bell 412SP on the ground], photograph, February 1990; (https://texashistory.unt.edu/ark:/67531/metadc950060/m1/1/: accessed May 11, 2024), University of North Texas Libraries, The Portal to Texas History, texashistory.unt.edu; .