APA (7th ed.) Zitazioa

ebrary, Inc, Hill, J., & Gale, T. (2009). Ecotourism and environmental sustainability: Principles and practice. Ashgate.

Chicago Style (17th ed.) Zitazioa

ebrary, Inc, Jennifer Hill, eta Tim Gale. Ecotourism and Environmental Sustainability: Principles and Practice. Farnham, England ; Burlington, VT: Ashgate, 2009.

MLA (9th ed.) Zitazioa

ebrary, Inc, et al. Ecotourism and Environmental Sustainability: Principles and Practice. Ashgate, 2009.