Ronald H Affolter
Samuel Hibbert
S. E Heermann
C. F. Zincken
United Nations. Secretariat. Technical Assistance Administration.
Robert Glenk
Robert B. Finkelman
Paul Kaunert
Unknown Author
Committee for Economic Development of Australia.
James Thomas Richardson
M. J. Purdy
Gunther Kühne
Rolf Schniotalle
Georg-Agricola-Gesellschaft. Jahrestagung
Geological Survey of Canada.
Maciej Ławniczak
V. M. Nahirnyĭ
S. K. Acharyya