Eckholm, E. P. (1978). Disappearing species: The social challenge. Worldwatch Institute.
Lua i Stíl Chicago (17ú heag.)Eckholm, Erik P. Disappearing Species: The Social Challenge. [Washington]: Worldwatch Institute, 1978.
Lua MLA (8ú heag.)Eckholm, Erik P. Disappearing Species: The Social Challenge. Worldwatch Institute, 1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.