@book{232500,
	author = {Martin, John H. and Waldren, Richard P.},
	title = {Principles of field crop production /},
	publisher = {Pearson Prentice Hall,},
	year = {c2006.},
	address = {Upper Saddle River, N.J. :},
	edition = {4th ed.},
	url = {http://www.loc.gov/catdir/toc/ecip054/2004028707.html}
}