United States. Army. Engineer Reproduction Plant, and United States. Army. Air Service. Landing facilities and proposed airway system in the United States, 1924. Washington, D.C.: Army Air Service, 1924. Web. 25 Apr 2025. <https://ark-dc3dev.bpl.org/ark:/50959/mc87pq96s>.

United States. Army. Engineer Reproduction Plant, & United States. Army. Air Service. (1924). Landing facilities and proposed airway system in the United States, 1924 [Map]. Retrieved from https://ark-dc3dev.bpl.org/ark:/50959/mc87pq96s

United States. Army. Engineer Reproduction Plant, and United States. Army. Air Service. "Landing facilities and proposed airway system in the United States, 1924." Map. Washington, D.C.: Army Air Service, 1924. Digital Commonwealth, https://ark-dc3dev.bpl.org/ark:/50959/mc87pq96s (accessed April 25, 2025).