1. Reference Diversity inJCR, JM, andJMR: A Reexamination and Extension of Tellis, Chandy, and Ackerman (1999)
2. Campbell, Donald T. and Julian C. Stanley (1963), Experimental and Quasi-Experimental Designs for Research, Chicago: Rand McNally.
3. Shadish, William R., Thomas D. Cook, and Donald T. Campbell (2002), Experimental and Quasi-Experimental Designs for Generalized Causal Inference, Boston: Houghton Mifflin.
4. Siegel, Lee (2001) The Metaphysical Club, Harper’s Magazine (October), 85-90.