APA-viite (7. p.)
Allen, W. L. National Geographic: Vol. 191, no. 1, January 1997. National Geographic Society.
Chicago-viite (17. p.)
Allen, William L. National Geographic: Vol. 191, No. 1, January 1997. Washington, EUA: National Geographic Society.
MLA-viite (9. p.)
Allen, William L. National Geographic: Vol. 191, No. 1, January 1997. National Geographic Society.
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