Mineral processing in developing countries / United Nations Radetzki, Marian. Zorn, Stephen. United Nations Industrial Development Organization. Mineral industries Developing countries. HD9506.D452 R33 1980 338.2 19 UNM At head of title: United Nations Industrial Development Organization. Prepared by Marian Radetzki and Stephen Zorn. "ID/253"--P. 4 of cover. "United Nations publication sales no. E.80.II.B.5"--P. 4 of cover. New York : United Nations, 1980. 1980. 1980 Text xii, 143 p. : eng Developing countries.