1.		Integrating sustainability into business : a management guide for responsible tour operations / Xavier Font, Janet Cochrane; United Nations Environment Programme Autor: Font, Xavier Coautor: ; Cochrane, Janet Co col. autor sec.: United Nations Environment Programme COTA(S): 11919
2.		Tour Guiding Research : Insights, Issues and Implications / Weiler, Betty Autor: Weiler, Betty; Black, Rosemary Co col. autor sec.: ; United Nations Environment Programme COTA(S): 16742