Delta Air Lines System Timetable April 1, 1990
MLA
Delta Air Lines, Inc.. "Delta Air Lines System Timetable April 1, 1990." Delta Flight Museum. 1990-04-01, https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19900401.
APA
Delta Air Lines, Inc. (1990-04-01). Delta Air Lines System Timetable April 1, 1990. Retrieved from https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19900401
Chicago
Delta Air Lines, Inc.. "Delta Air Lines System Timetable April 1, 1990." 1990-04-01. May 8, 2026. https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19900401.
