@book{26364,
	author = {Wilmarth, M. Grace},
	title = {The geologic time classification of the United States Geological survey compared with other classifications, accompanied by the original definitions of era, period and epoch terms.},
	publisher = {Govt. print. off.,},
	year = {1925.},
	series = {U. S. Geological survey. Bulletin},
	address = {Washington,}
}