@article{216816, recid = {216816}, author = {Singer, D. A. and Menzie W. David. and Long, Keith R.}, title = {A simplified economic filter for open-pit gold-silver mining in the United States /}, publisher = {U.S. Geological Survey,}, address = {[Menlo Park, CA] :}, pages = {10 p. :}, year = {1998}, note = {Cover title.}, url = {http://library.usi.edu/record/216816}, }