@book{1970,
	author = {Simmons, George Finlay, and Krantz, Steven G.},
	title = {Differential equations: theory, technique, and practice. /},
	publisher = {McGraw-Hill Higher Education,},
	year = {c2007.},
	address = {New York, NY :},
	url = {http://www.loc.gov/catdir/enhancements/fy0634/2005051118-d.html}
}