Carter, A. A., & Gould, S. J. (1999). The art of national geographic: Century of illustration (Special catalog edition.). National Geographic Society.
Chicago-viite (17. p.)Carter, Alice A., ja Stephen Jay Gould. The Art of National Geographic: Century of Illustration. Special catalog edition. Washington, D.C.: National Geographic Society, 1999.
MLA-viite (9. p.)Carter, Alice A., ja Stephen Jay Gould. The Art of National Geographic: Century of Illustration. Special catalog edition. National Geographic Society, 1999.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.