Characteristics of main seam ' s coal quality of shanbei jurassic coalfield and its utilizing prospect 陕北侏罗纪煤田主要煤层煤质特征及利用方向
2.
Characteristics of faults in main seams of laoyingshan mine and their influence upon arrangement of development and working faces 老鹰山矿主采煤层内断层的特征及其对采掘工作面布置的影响