Walter, Sven. "Epiphenomenalism". Internet Encyclopedia of Philosophy. University of Bielefeld. Archived from the original on 23 September 2013. Retrieved 10 October 2013.
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Walter, Sven. "Epiphenomenalism". Internet Encyclopedia of Philosophy. University of Bielefeld. Archived from the original on 23 September 2013. Retrieved 10 October 2013.