Bryan, C. D. B. (1987). The National Geographic Society: 100 years of adventure and discovery. H.N. Abrams.
Citazione stile Chigago Style (17a edizione)Bryan, C. D. B. The National Geographic Society: 100 Years of Adventure and Discovery. New York: H.N. Abrams, 1987.
Citatione MLA (9a ed.)Bryan, C. D. B. The National Geographic Society: 100 Years of Adventure and Discovery. H.N. Abrams, 1987.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.