@book{25750,
	author = {Emmons, William H.},
	title = {The enrichment of ore deposits /},
	publisher = {Govt. print. off.,},
	year = {1917.},
	series = {U. S. Geological survey.  Bulletin  625.},
	address = {Washington :},
	note = {At head of title: Dept. of the interior.}
}