Microscopic research on the structure of coke produced from various Polish coals = Badania mikroskopowe struktury koksów z różnych wȩgli Polskiego Zagłȩbia /

by Krajewski, Jan
Warszawa, Poland : Published for the National Science Foundation and the Department of the Interior, by the Central Institute for Scientific and Technical Documentation, 1960

Electrostatic separation of coals = Wzbogacanie elektrostatyczne węgli /

by Krajewski, Jan
Warsawa, Poland : Published for the National Science Foundation and the Department of the Interior by the Central Institute for Scientific and Technical Documentation, 1960

The electrostatic enrichment of coals, part II /

by Krajewski, Jan, 1935-
Warszawa, Poland : Published for the National Science Foundation and the Dept. of the Interior by Centralny Instytut Dokumentacji Nuakowo-Technicznej, 1961