Environmental management for the 1990's : proceedings of the Symposium on Environmental Management for the 1990's, Denver, Colorado, February 25-28, 1991 / editors, D.J. Lootens, W.M. Greenslade, J.M. Barker ; sponsored by Society for Mining, Metallurgy, and Exploration ; cosponsored by Northwest Mining Association, Colorado Mining Association. Littleton, Colo. : The Society, 1991. viii, 379 p. : ill.