@book{52352,
	author = {Hulley Stephen B.  and Cummings Steven R. },
	title = { Designing clinical research/},
	publisher = {Wolters Kluwer Health/Lippincott Williams & Wilkins,},
	year = {c2013},
	address = { Philadelphia:},
	edition = {4th.edition},
	note = {previous edition published in 2007 by lippincott william &wilkins,a walters kluwer business}
}