1. Abramowitz, A. I. (1991). Incumbency, campaign spending, and the decline of competition in U.S. House elections. Journal of Politics, 53(1), 34–56.
2. Amman, S. L. (2010). A political campaign message in 140 characters or less: The use of Twitter by U.S. Senate candidates in 2010. Retrieved from http://ssrn.com /abstract=1725477
3. Ancu, M. (2011). From soundbite to textbite: Election 2008 comments on Twitter. In J. A. Hendricks & L. L. Kaid (Eds.), Techno politics in presidential campaigning: New voices, new technologies, and new voters (pp. 11–21). New York, NY: Routledge.
4. Arnold, R. D. (2004). Congress, the press, and political accountability. Princeton, NJ: Princeton University Press.
5. Balch, G. I. (1974). Multiple indicators in survey research: The concept “sense of political efficacy”. Political Methodology, 1, 1–43.