1. American Association for Public Opinion Research. 2006. Standard definitions: Final dispositions of case codes and outcome rates for surveys, 4th ed. Lenexa: AAPOR.
2. Baker, Joseph O., and Buster G. Smith. 2009. The nones: Social characteristics of the religiously unaffiliated. Social Forces 87(3): 1251–1263.
3. Barna Group. 2007. Unchurched Population Nears 100 Million in the U.S. The Barna Group (March 19). http://www.barna.org/barna-update/article/12-faithspirituality/107-unchurched-population-nears-100-million-in-the-us . Accessed 3 March 2012.
4. Billingsley, Andrew. 1999. Mighty like a river: The black church and social reform. New York: Oxford University Press.
5. Cadge, Wendy, and Elaine Howard Ecklund. 2007. Immigration and religion. Annual Review of Sociology 33(1): 359–379.