@book{24600,
	author = {Havlin, John L.. ed. and Jacobsen, Jeffrey S,},
	title = {Soil Testing: Prospects for Improving Nutrient Recomendations /},
	publisher = {Soil Science Society of America,},
	year = {1994.},
	series = {SSSA Special Publication, Number 40},
	address = {Madison, Wisconsin :}
}