Per anno

 @article{granovetter-ajs78,
	Author = {Granovetter, Mark S.},
	Journal = {American Journal of Sociology},
	Month = may,
	Number = 6,
	Pages = {1360--1380},
	Publisher = {The University of Chicago Press},
	Title = {The Strength of Weak Ties},
	Url = {http://www.jstor.org/stable/2776392},
	Volume = 78,
	Year = 1973}