International Union for Conservation of Nature and Natural Resources. Commission on Education. East-Europe Committee, Čeřovský, J., Boşcaiu, N., Hoffmann, G., Ijtal, A., Maršáková, M., . . . Wojda, M. (1988). Nature conservation in the socialist countries of East-Europe (Second, revised and enlarged edition.). Praha: Ministry of culture of the Czech socialist republic.

International Union for Conservation of Nature and Natural Resources. Commission on Education. East-Europe Committee, Jan Čeřovský, Nicolae Boşcaiu, Günther Hoffmann, Arvo Ijtal, Marie Maršáková, Taniu Michev, Enikö Szalay-Marzsó, and Mieczyslaw Wojda. Nature Conservation in the Socialist Countries of East-Europe. Second, revised and enlarged edition. Praha: Ministry of culture of the Czech socialist republic, 1988.

International Union for Conservation of Nature and Natural Resources. Commission on Education. East-Europe Committee, et al. Nature Conservation in the Socialist Countries of East-Europe. Second, revised and enlarged edition. Praha: Ministry of culture of the Czech socialist republic, 1988.