Full Idea
Indexicals do not refer; only tokens of an indexical refer
Gist of Idea
Indexical don't refer; only their tokens do
Source
François Recanati (Mental Files [2012], 5.1)
Book Reference
Recanati,François: 'Mental Files' [OUP 2012], p.57
A Reaction
Thus 'Thurs 23rd March 2013' refers, but 'now' doesn't, unless someone produces an utterance of it. This is why indexicals are sometimes called 'token-reflexives'.