Bryan, C. D. B. (1987). The National Geographic Society: 100 years of adventure and discovery. H.N. Abrams.
Chicago-viite (17. p.)Bryan, C. D. B. The National Geographic Society: 100 Years of Adventure and Discovery. New York: H.N. Abrams, 1987.
MLA-viite (9. p.)Bryan, C. D. B. The National Geographic Society: 100 Years of Adventure and Discovery. H.N. Abrams, 1987.
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