Delta Air Lines System Timetable 1968 April 1
MLA
Delta Air Lines, Inc.. "Delta Air Lines System Timetable 1968 April 1." Delta Flight Museum. 1968-04-01, https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19680401.
APA
Delta Air Lines, Inc. (1968-04-01). Delta Air Lines System Timetable 1968 April 1. Retrieved from https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19680401
Chicago
Delta Air Lines, Inc.. "Delta Air Lines System Timetable 1968 April 1." 1968-04-01. July 24, 2025. https://dlg.galileo.usg.edu/do:delta_dal-tt_dal-tt-19680401.
