Dyfyniad APA

Eckholm, E. P. (1978). Disappearing species: The social challenge. Worldwatch Institute.

Dyfyniad Arddull Chicago

Eckholm, Erik P. Disappearing Species: The Social Challenge. [Washington]: Worldwatch Institute, 1978.

Dyfyniad MLA

Eckholm, Erik P. Disappearing Species: The Social Challenge. Worldwatch Institute, 1978.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.