Zero anaphora is the use of a gap, in a phrase or clause, that has an anaphoric function similar to a pro-form. |
It is often described as “referring back” to an expression that supplies the information necessary for interpreting the gap. |
Hartmann, R.R.K., and F.C. Stork. 1972.Dictionary of language and linguistics. London: Applied Science.
Crystal, David. 1985.A dictionary of linguistics and phonetics. 2nd edition. New York: Basil Blackwell.