The Spread of Obesity in a Large Social Network over 32 Years, Nicholas A. Christakis, M.D., Ph.D., M.P.H., and James H. Fowler, Ph.D. N Engl J Med 2007; 357:370-379.
The Collective Dynamics of Smoking in a Large Social Network, Nicholas A. Christakis, M.D., Ph.D., M.P.H., and James H. Fowler, Ph.D., N Engl J Med 2008; 358:2249-2258.
Alone in the crowd: The structure and spread of loneliness in a large social network, Cacioppo, John T., Fowler, James H., Christakis, Nicholas A., Journal of Personality and Social Psychology 97:6, pp 977-991, 2009
http://psycnet.apa.org/journals/psp/97/6/977.html
Dynamic spread of happiness in a large social network: longitudinal analysis over 20 years in the Framingham Heart Study, James H Fowler, Nicholas A Christakis, BMJ 2008; 337 doi: 10.1136/bmj.a2338
http://www.bmj.com/content/337/bmj.a2338

Homophily and Contagion Are Generically Confounded in Observational Social Network Studies, Cosma Rohilla Shalizi, Andrew C. Thomas, Sociological Methods Research May 2011 vol. 40 no. 2 211-239
http://smr.sagepub.com/content/40/2/211
The Spread of Evidence-Poor Medicine via Flawed Social-Network Analysis, Russell Lyons, Statistics, Politics, and Policy, Volume 2, Issue 1, Pages 1 27, ISSN (Online) 2151-7509, DOI:10.2202/2151-7509.1024, May 2011.
http://www.degruyter.com/view/j/spp.2011.2.1/spp.2011.2.1.1024/spp.2011.2.1.1024.xml
Distinguishing influence-based contagion from homophily-driven diffusion in dynamic networks, Sinan Aral, Lev Muchnik and Arun Sundararajan, PNAS December 22, 2009 vol. 106 no. 51 21544-21549.
http://www.pnas.org/content/106/51/21544.short

Social Contagion Theory: Examining Dynamic Social Networks and Human Behavior Nicholas A. Christakis, James H. Fowler (Unpublished: Submitted on 24 Sep 2011).
http://arxiv.org/abs/1109.5235