@book {1661,
	title = {Effects of Persistent Volcanic Ash on Douglas-fir in Northern Idaho },
	year = {1987},
	publisher = {U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station},
	organization = {U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station},
	address = {Ogden, Utah},
	author = {Bilderback, D.E. and Carlson, C.E.}
}
