@book{22655,
	author = {Babbie, Earl R.},
	title = {The practice of social research },
	publisher = {Cengage Learning},
	year = {2017},
	address = {Delhi},
	edition = {Thirteenth edition.},
	note = {Previous edition: 2010.},
	url = {http://www.loc.gov/catdir/enhancements/fy1506/2011925964-t.html}
}