@book{19730,
	author = {Clark, Ruth Colvin, and Mayer, Richard E.,},
	title = {E-learning and the science of instruction :},
	publisher = {Wiley,},
	year = {2016},
	address = {Hoboken, New Jersey :},
	edition = {4th ed.},
	url = {http://catalogimages.wiley.com/images/db/jimages/9781119158660.jpg}
}