@book{7652,
	author = {Richards, Edgar.},
	title = {Principles and methods of soil analysis.},
	publisher = {Govt. print. off.,},
	year = {1886.},
	series = {U. S. Dept. of agriculture. Division of Chemistry. Bulletin},
	address = {Washington,},
	url = {http://hdl.loc.gov/loc.gdc/scd0001.00027817233}
}