@book{27439,
	author = {United States.},
	title = {Operating regulations to govern coal-mining methods and the safety and welfare of miners},
	publisher = {U.S. Govt. print. off.,},
	year = {1938.},
	address = {Washington,},
	edition = {Second edition.},
	note = {At head of title: United States Department of the interior.}
}