Name Info Provider Link
Flu Shot free resource MedlinePlus Health Information https://medlineplus.gov/flushot.html
subscription/membership/fee required Ovid Technologies, Inc. http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=21711314.ui
subscription/membership/fee required Wiley https://doi.org/10.1111/j.1751-0813.2011.00769.x