Fried Linda P, Bentley Margaret E, Buekens Pierre, Burke Donald S, Frenk Julio J, Klag Michael J, Spencer Harrison C
Mailman School of Public Health, Columbia University, New York, NY, USA.
Lancet. 2010 Feb 13;375(9714):535-7. doi: 10.1016/S0140-6736(10)60203-6.