Communications and Beacons on Air Routes, report, March 1922; (https://digital.library.unt.edu/ark:/67531/metadc277446/m1/1/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .
Communications and Beacons on Air Routes, report, March 1922; (https://digital.library.unt.edu/ark:/67531/metadc277446/m1/1/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .