1.		Participant crowding and physical contact rates of whale shark tours on Isla Holbox, Mexico / Jackie A. Ziegler, Philip Dearden, Rick Rollins Autor: Ziegler, Jackie Coautor: ; Dearden, Philip Rollins, Rick B.
2.		Participant crowding and physical contact rates of whale shark tours on Isla Holbox, Mexico / Jackie A. Zielgler [et al.] Autor: Zielgler, Jackie A. Coautor: ; Dearden, Philip Rollins, Rick B.