@book{47146,
	author = {Berhanu, Shiferaw and Cordaro, Paulo D.},
	title = {An introduction to involutive structures /},
	publisher = {Cambridge University Press,},
	year = {c2008},
	address = {Cambridge ;},
	url = {http://www.loc.gov/catdir/enhancements/fy0835/2008274291-t.html}
}