National Geographic Socity. Special Publication Division & Gray, W. B. (1978). Power of nature. Prepared by the Special Publication Division, National Geographic Society.
Lua i Stíl Chicago (17ú heag.)National Geographic Socity. Special Publication Division agus William B. Gray. Power of Nature. Washington, DC: Prepared by the Special Publication Division, National Geographic Society, 1978.
Lua MLA (9ú heag.)National Geographic Socity. Special Publication Division agus William B. Gray. Power of Nature. Prepared by the Special Publication Division, National Geographic Society, 1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.