APA (7th ed.) Citation

Rookmaaker, K. The World As It Once Was. IUCN.

Chicago Style (17th ed.) Citation

Rookmaaker, Kees. The World As It Once Was. IUCN.

MLA (9th ed.) Citation

Rookmaaker, Kees. The World As It Once Was. IUCN.

Warning: These citations may not always be 100% accurate.