6]王淑兰,张远航,钟流,等.珠江三角洲城市间空气污染的相互影响中国环境科学,2005(2) 133-137. Efficiency levels and regulation effects of coal industry in China Abstract Key words coal industry; efficiency; regulation effects5 [6] 王淑兰, 张远航, 钟流, 等. 珠江三角洲城市间空气污染的相互影响[J]. 中国环境科学, 2005 (2): 133-137. Efficiency levels and regulation effects of coal industry in China Abstract …… Key words coal industry; efficiency; regulation effects;……