@book{25439,
	author = {Dale, T. Nelson and Hillebrand, W. F.},
	title = {Slate in the United States,},
	publisher = {Govt. print. off.,},
	year = {1914.},
	series = {U. S. Geological survey. Bulletin},
	address = {Washington,},
	note = {Many plates printed on both sides of leaves.}
}