Subsidence problems due to abandoned pillar workings in coal seams[J] . F. G. Bell,I. A. de Bruyn.Bulletin of Engineering Geology and the Environment . 1999 (3)
Subsidence problems due to abandoned pillar workings in coal seams[J] . F. G. Bell,I. A. de Bruyn.Bulletin of Engineering Geology and the Environment . 1999 (3)