World heritage twenty years later : based on papers presented at the World Heritage and other workshops held during the IVth World Congress on National Parks and Protected Areas, Caracas, Venezuela, February 1992 /
Thorsell, Jim.
IUCN Commission on National Parks and Protected Areas.
Unesco.World Heritage Committee.
World Congress on National Parks and Protected Areas(4th :1992 :Caracus, Venezuela)
Gland, Switzerland ; Cambridge : IUCN in collaboration with UNESCO's World Heritage Committee,
1992.
Includes bibliographies.