@book{8921,
	author = {Helms, Marilyn M.},
	title = {Student study guide for use with Operations and supply management / F. Robert Jacobs, Richard B. Chase, Nicholas J. Aquilano. !2th ed. :},
	publisher = {McGraw-Hill,},
	year = {2009.},
	address = {Boston :},
	edition = {12th  ed.}
}