@book{89512,
	author = {Hedström, Peter},
	title = {Social mechanisms  an analytical approach to social theory},
	publisher = {Cambridge University Press},
	year = {1998},
	series = {Studies in Rationality and Social Change},
	address = {Cambridge (Inglaterra)},
	url = {http://www.loc.gov/catdir/toc/cam026/97011413.html}
}