Kaushal, P., & Sharma, S. P. (2011). Ecological and environmental impact of tourism. Kanishka.
Chicago Style aipamenaKaushal, Prerna, and Shashi Prabha Sharma. Ecological and Environmental Impact of Tourism. New Delhi: Kanishka, 2011.
MLA aipamenaKaushal, Prerna, and Shashi Prabha Sharma. Ecological and Environmental Impact of Tourism. Kanishka, 2011.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.