1. Galea, M., & Tracy, S. (2007). Participation rates in epidemiological studies. Annals of Epidemiology, 17, 643–653.
2. Krosnick, J. A. (1999). Survey research. Annual Review of Psychology, 50, 537–567.
3. Shih, T. H., & Fan, X. (2007). Response rates and mode preferences in web-mail mixed-mode surveys: A meta-analysis. International Journal of Internet Science, 2, 59–82.
4. Robling, M. R., Ingledew, D. K., Greene, G., Sayers, A., Shaw, C., Sander, L., et al. (2010). Applying an extended theoretical framework for data collection mode to health services research. BMC Health Services Research, 10, 180.
5. Millar, M. M., O’Neill, A. C., & Dillman, D. A. (2009). Are mode preferences real? Pullman, WA: Washington State University, Social & Economic Sciences Research Center (SESRC). 2009 February. Technical report: 09-003. Retrieved from http://www.sesrc.wsu.edu/dillman/papers/Tech%20Report%20FINAL%20Feb%2023.pdf .