1. Abelson, R. P., Loftus, E. F., & Greenwald, A. G. (1992). Attempts to improve the accuracy of self-reports of voting. In J. M. Tanur (Ed.), Questions about questions (pp. 138–153). New York: Russell Sage.
2. Babbie, E., & Mouton, J. M. (2001). The practice of social research. Cape Town: Oxford University Press.
3. Bishop, G. F., Hippler, H. J., Schwarz, N., & Strack, F. (1988). A comparison of response effects in self-administered and telephone surveys. In R. M. Groves, P. P. Biemer, L. E. Lyberg, J. T. Massey, W. L. Nicholls II, & J. Waksberg (Eds.), Telephone survey methodology (pp. 321–334). New York: Wiley.
4. Calsyn, R. J., Roades, L. A., & Calsyn, D. S. (1992). Acquiescence in needs assessment studies of the elderly. The Gerontologist, 32, 246–252.
5. Clancy, K. J., & Wachsler, R. A. (1971). Positional effects in shared-cost surveys. Public Opinion Quarterly, 35, 258–265.