Powell, Guido A., Kate Zinszer, Aman D. Verma, Lawrence C. Madoff, Chi Bahk, John S. Brownstein, and David Buckeridge. 2016. “Monitoring Media Content About Vaccines in the United States: Data from the Vaccine Sentimeter”. Online Journal of Public Health Informatics 8 (1). https://doi.org/10.5210/ojphi.v8i1.6487.