@book{57746,
	author = {"Black, C.A.,Et al�"},
	title = {Methods of Soil analysis.Part II : Chemical &  Micrological properties  (Agronomy Monographs No. 9) 2nd printing 1969},
	publisher = {American Soc. Agronomy},
	year = {"Madison, Wisconsin"},
	address = {1965}
}