International Geographical Union : European Regional Conference : Dynamische Unterschiede des Verkarstungsprocesses in den Mikroräumen.
International Geographical Union : European Regional Conference : Symposium of agricultural typology and agricultural settlements S. 5. : Some characteristic features of the industrial development of the southern Great Plain.
International Geographical Union : European Regional Conference : Symposium of agricultural typology and agricultural settlements S. 5. : field trips.
International Geographical Union : European Regional Conference : Symposium on Karst-Morphogenesis : a detailed exposition of the study tours.