@book{95957,
	author = {Symposium on Soil Testing. Sampling Correlation, Cablibration and Interpretation. Madison Soil Science Society of America, Dec.1-5,1987.},
	title = {Soil testing: Sampling, Correlation, Calibration and Interpretation ; proceedings},
	publisher = {Soil Science Society of America Inc.},
	year = {1987},
	series = {SSSA Special Publication no.21},
	address = {Madison}
}