Delta Air Lines System Timetable 1939 July 15
MLA
Delta Air Corporation. "Delta Air Lines System Timetable 1939 July 15." Delta Flight Museum. 1939-07-15, https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19390715.
APA
Delta Air Corporation (1939-07-15). Delta Air Lines System Timetable 1939 July 15. Retrieved from https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19390715
Chicago
Delta Air Corporation. "Delta Air Lines System Timetable 1939 July 15." 1939-07-15. May 7, 2026. https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19390715.
