@book{4,
	author = {Illowsky, Barbara, and Dean, Susan L., and OpenStax College,},
	title = {Introductory statistics /},
	publisher = {OpenStax College, Rice University,},
	year = {[2013]},
	address = {Houston, Texas :},
	note = {Includes index.},
	url = {https://open.umn.edu/opentextbooks/textbooks/196}
}