APA (7th ed.) Citation

United States. Post Office Department. (1931). Schedule of steamers appointed to convey mails from U.S. to foreign countries, also to Territory of Hawaii and to possessions of U.S.; schedule of air mail routes available for dispatch of articles mailed in U.S. to and in foreign countries. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Schedule of Steamers Appointed to Convey Mails from U.S. to Foreign Countries, Also to Territory of Hawaii and to Possessions of U.S.; Schedule of Air Mail Routes Available for Dispatch of Articles Mailed in U.S. to and in Foreign Countries. [Washington]: GPO, 1931.

MLA (9th ed.) Citation

United States. Post Office Department. Schedule of Steamers Appointed to Convey Mails from U.S. to Foreign Countries, Also to Territory of Hawaii and to Possessions of U.S.; Schedule of Air Mail Routes Available for Dispatch of Articles Mailed in U.S. to and in Foreign Countries. GPO, 1931.