@book{26647,
	author = {Condra, Geo. E.},
	title = {The stratigraphy of the Pennsylvanian system in Nebraska,},
	publisher = {Printed by authority of the state of Nebraska [The University of Nebraska press]},
	year = {1927.},
	series = {Nebraska.  Geological survey.  Bulletin I, 2d ser.},
	address = {[Lincoln]}
}