@book{9301,
	author = {Unknown.},
	title = {Microsoft ms-dos upgrade operating system user's guide /},
	publisher = {Microsoft Corp,},
	year = {1994.},
	address = {[S.l.] :},
	url = {http://www.amazon.com/exec/obidos/ASIN/B000X3HDQI/chopaconline-20}
}