@book{130854,
	author = {Føllesdal, Dagfinn.},
	title = {Referential opacity and modal logic /},
	publisher = {Routledge,},
	year = {2004.},
	series = {Studies in philosophy},
	address = {New York :},
	url = {http://www.loc.gov/catdir/enhancements/fy0647/2002017877-d.html}
}