by Alan R. Wallace ... [and others] ; with a section on Platinum-group-element (PGE) potential of the Humboldt mafic complex, by Michael L. Zientek, Gary B. Sidder, and Robert A. Zierenberg
by the U.S. Geological Survey Mineral Resource Assessment Team ; recompilation by Paul Schruben as a subtask of the Global Minerals Resources Assessment Project