BARBER, T. K.
(1973) "Pitfalls in research: nine investigator experimenter effects," pp. 382-404 in R. M. W. Travers (ed.) Second Handbook of Research on Teaching. Chicago: Rand McNally.
2.
ROSENTHAL, R.
and R. L. ROSNOW (1969) Artifacts in Behavioral Research. New York: Academic Press.
3.
SCHERR, B. A.
and E. M. BABB (1975) "Pricing public goods: an experiment with two proposed pricing systems."Public Choice23 (Fall): 35-48.