IUCN monograph
International Union for Conservation of Nature and Natural Resources
N. M. Wace and M. W. Holdgate
International Union for Conservation of Nature and Natural Resources 1976 IUCN monograph no. 6
Available at 1 libraries
Norman Myers
International Union for Conservation of Nature and Natural Resources 1976 IUCN monograph no. 5
Available at 2 libraries
Edward Mitchell
International Union for Conservation of Nature and Natural Resources 1975 IUCN monograph no. 3
International Union for Conservation of Nature and Natural Resources 1975 IUCN monograph no. 4