@book{250,
	author = {M'Gonigle, John W. and Dalrymple, G. Brent},
	title = {40Ar/39Ar ages of some Challis Volcanic Group rocks and the initiation of Tertiary sedimentary basins in southwestern Montana /},
	publisher = {U.S. Govt. Print. Off.,},
	year = {1996},
	series = {Bulletin ;},
	address = {Washington :}
}