@article{Fowler2008,
author = {Fowler, J.H.  and Christakis, N.A},
title= {Dynamic spread of happiness in a large social network: longitudinal analysis over 20 years in the Framingham Heart Study},
year = {2008},
doi = {10.1136/bmj.a2338},
journal = {British Medical Journal },
volume = {337},
pages = {a2338},
}