@book{25183,
	author = {Marshall, R. B. and Geological Survey of Ohio.},
	title = {Results of spirit leveling in Ohio, 1911.},
	publisher = {Govt. Print. Off.,},
	year = {1912.},
	series = {U.S. Geological survey. Bulletin 518},
	address = {Washington,},
	note = {Includes index.}
}