4ZIPPER C,BALFOUR W,ROTH R,et al.Domestic water supply impacts by underground coal mining in Virginia,USA[J].Environmental Geology,1997,29(1):84-93.
5BELL F G,BULLOCK S,HALBICH T,et al.Environmental impacts associated with an abandoned mine in the Witbank Coalfield,South Africa[J].International Journal of Coal Geology,2001(45):195-216.
