Ali, M.; Sur, D.; Lopez, A. L.; Kanungo, S.; Ochiai, R. L.; Manna, B.; Kim, D. R.; Deen, J.; Bhattacharya, S. K.; Clemens, J. D. Community Participation in Two Vaccination Trials in Slums of Kolkata, India: A Multi-Level Analysis. J Health Popul Nutr 2010, 28, 450-457.