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Productivity of underground coal workings
(1965)
Productivity in Soviet coal mining, 1928-1964
Butler, Charles E., (1976)
Legal aspects of coal leasing and sales, and strip mining reclamation in North Dakota
Beck, Robert E., (1973)
Proizvoditel'nost truda v ugol'noj promyšlennosti SSSR v 6. pjatiletke
Charčenko, Aleksej Kondrat'evič, (1956)
Ugol'naja promyšlennost' Kitajskoj Narodnoj Respubliki
Bazenov, Ivan I., (1959)