9Aitmatov IT,Vdovin K D,Kejogulov K Ch, et al. State of stress in rock and rock - burst proneness in seimicative folded areas[ M]. Procs. of 6th ISRM. Canada, 1987.
10BouskaV, Pesek J, Sykorova I. Probable modes of occurrence of chemical elements in coal. Acta Montana, Ser. B. Fuel, Carbon, Mineral Processing, Praha, 2000,10(117) :53 -90.