1. BERELSON, B. and G. STEINER (1964) Human Behavior: An Inventory of Scientific Findings. New York: Harcourt, Brace & World.
2. CAMPBELL, D. and J. STANLEY (1963) Experimental and Quasi-experimental Designs for Research. Chicago: Rand McNally.
3. CAMPBELL, A., P. CONVERSE., W. MILLER., and D. STOKES (1960) The American Voter. New York: John Wiley.
4. Centraal Bureau voor de Statistiek (1971) Statistiek der Verkiezingen 1970. apos;s-Gravenhage: Staatsuitgeverij.