APA aipamena

Bien, A. (1999). Errors and principles of action of ecotourism projects.

Chicago Style aipamena

Bien, Amos. Errors and Principles of Action of Ecotourism Projects. 1999.

MLA aipamena

Bien, Amos. Errors and Principles of Action of Ecotourism Projects. 1999.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.