@book{25197,
	author = {Marshall, R. B. and Pennsylvania.},
	title = {Results of spirit leveling in Pennsylvania, 1899 to 1911, inclusive.},
	publisher = {Govt. Print. Off.,},
	year = {1912.},
	series = {U.S. Geological survey. Bulletin 515},
	address = {Washington,},
	note = {Includes index.}
}