International Union for Conservation of Nature and Natural Resources & Goudswaard, J. (1972). Environmental education in an urban society: Proceedings of the ninth regional conference of the North-West Europe Committee ... held at Rotterdam ... 1971. International Union for Conservation of Nature and Natural Resources.
Chicago (17e ed.) BronvermeldingInternational Union for Conservation of Nature and Natural Resources en J. Goudswaard. Environmental Education in an Urban Society: Proceedings of the Ninth Regional Conference of the North-West Europe Committee ... Held at Rotterdam ... 1971. Morges: International Union for Conservation of Nature and Natural Resources, 1972.
MLA (8e ed.) BronvermeldingInternational Union for Conservation of Nature and Natural Resources en J. Goudswaard. Environmental Education in an Urban Society: Proceedings of the Ninth Regional Conference of the North-West Europe Committee ... Held at Rotterdam ... 1971. International Union for Conservation of Nature and Natural Resources, 1972.