@book{16915,
	author = {Brown, J. R. and Soil Science Society of America. SSSA. },
	title = {Soil testing :},
	publisher = {Soil Science Society of America,},
	year = {1987.},
	series = {SSSA special publication ;},
	address = {Madison, WI :},
	note = {3a. reimpresión 1990.}
}