Cita APA (7a ed.)
(1977). National geographic index: 1947-1976 (inclusive) (ed.). National geographic society.
Cita Chicago Style (17a ed.)
National Geographic Index: 1947-1976 (inclusive). ed. Washington,D.C.: National geographic society, 1977.
Cita MLA (9a ed.)
National Geographic Index: 1947-1976 (inclusive). ed. National geographic society, 1977.
Precaución: Estas citas no son 100% exactas.