@book{1969,
	author = {Ledder, Glenn.},
	title = {Differential equations: a modeling approach. /},
	publisher = {McGraw-Hill Higher Education,},
	year = {c2005.},
	address = {Boston :},
	note = {Includes index.},
	url = {http://www.loc.gov/catdir/description/mh051/2004049354.html}
}