论坛币300求助文献：

1。Sources of deep coal mine productivity change, 1962–1975

作者：Baker, J.G.

期刊：The Energy Journal 1981，2, 95–106.

2。Sources of productivity decline in U.S. coal mining, 1972–1977.

作者：Kruvant, W.J., Moody, C.E., Valentine, P.L.

期刊：The Energy Journal 1982，3, 53–70.

多谢各位