ebrary, Inc, Hill, J., & Gale, T. (2009). Ecotourism and environmental sustainability: Principles and practice. Ashgate.
Čikaški stil citiranja (17. izdanje)ebrary, Inc, Jennifer Hill, i Tim Gale. Ecotourism and Environmental Sustainability: Principles and Practice. Farnham, England ; Burlington, VT: Ashgate, 2009.
MLA način citiranja (9. izdanje)ebrary, Inc, et al. Ecotourism and Environmental Sustainability: Principles and Practice. Ashgate, 2009.
Upozorenje: Ovi citati možda nisu uvijek 100% točni.