@book{27157,
	author = {Illinois State Geological Survey and Thiessen, Gilbert,},
	title = {Contributions to the study of coal:},
	publisher = {Printed by authority of the state of Illinois,},
	year = {1934.},
	series = {Its Report of investigations},
	address = {Urbana, Illinois,},
	note = {At head of title: State of Illinois. Department of Registration and Education. Division of the State Geological Survey.}
}