Eckholm, E. P. (1978). Disappearing species: The social challenge. Worldwatch Institute.
Chicago Style aipamenaEckholm, Erik P. Disappearing Species: The Social Challenge. [Washington]: Worldwatch Institute, 1978.
MLA aipamenaEckholm, Erik P. Disappearing Species: The Social Challenge. Worldwatch Institute, 1978.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.