APA (7th ed.) Citation

U.S. Board on Geographical Names & U.S. Army Map Service. A.M.S. S401. (1944). Gazetteer to maps of the Philippine Islands, map series AMS S401 scale 1: 500,000 (2nd ed.). Army Map Service.

Chicago Style (17th ed.) Citation

U.S. Board on Geographical Names and U.S. Army Map Service. A.M.S. S401. Gazetteer to Maps of the Philippine Islands, Map Series AMS S401 Scale 1: 500,000. 2nd ed. Washington: Army Map Service, 1944.

MLA (9th ed.) Citation

U.S. Board on Geographical Names and U.S. Army Map Service. A.M.S. S401. Gazetteer to Maps of the Philippine Islands, Map Series AMS S401 Scale 1: 500,000. 2nd ed. Army Map Service, 1944.