1. Chisholm, R. (1957). Perceiving. Ithaca, N.Y.: Cornell University Press.
2. Colyvan, M. (2008). Indispensability arguments in the philosophy of mathematics. In Edward N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Fall 2008 Edition). URL = http://plato.stanford.edu/archives/fall2008/entries/mathphil-indis/ .
3. Crane, T. (2008) The problem of perception. In Edward N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Fall 2008 Edition). URL = http://plato.stanford.edu/archives/fall2008/entries/perception-problem/ .
4. Cummins, R. (1996). Representations, targets and attitudes. Cambridge, MA: MIT Press.
5. Dahlbom, B. (Ed.). (1995). Dennett and his critics. Oxford: Blackwell.