@book{36129,
	author = {Cocchiarella, Nino B. and Freund, Max A., and ebrary, Inc.},
	title = {Modal logic},
	publisher = {Oxford University Press,},
	year = {2008.},
	address = {Oxford ;},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10246251}
}