@book{35806,
	author = {Wallis, W.D. and SpringerLink (Online service)},
	title = {A Beginner's Guide to Discrete Mathematics},
	publisher = {Birkhäuser Boston,},
	year = {2012.},
	address = {Boston :},
	edition = {Second Edition.},
	url = {http://dx.doi.org/10.1007/978-0-8176-8286-6}
}