Search U.S. government technical reports digitized or harvested by TRAIL.
Basic estimated capital investment and operating costs for underground bituminous coal mines :mines with annual production of 1.03 to 3.09 million tons from a 48-inch coalbed : revision of Information circular 8641
Basic estimated capital investment and operating costs for underground bituminous coal mines :mines with annual production of 1.06 to 4.99 million tons from a 72-inch coalbed
Basic estimated capital investment and operating costs for coal strip mines :revision of information circular 8661