@book{121032,
	author = {Elster, Jon,  and García Aldonate, Mario,},
	title = {Una introducción a Karl Marx /},
	publisher = {Siglo XXI de España,},
	year = {2020.},
	address = {Madrid :},
	url = {http://www.loc.gov/catdir/description/cam023/86004238.html}
}