Selected Geologic Factors Affecting Mining of the ...
Selected geologic factors affecting mining of the Pitts burgh coalbed, by C. M. McCulloch [and others. Washing ton] Bureau of Mines [1975] 72 p. illus., tables. ( Bureau of Mines. Report of investi gations 8093) Includes bibliography. 1. Coal mines and miningPennsylvania . 2. Coal mines and miningWest ia. 3.