Name Info Provider Link
Flu free resource MedlinePlus Health Information https://medlineplus.gov/flu.html
free resource Public Library of Science https://dx.plos.org/10.1371/journal.pmed.1000442
free resource PubMed Central https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21713000/
free resource Europe PubMed Central https://europepmc.org/abstract/MED/21713000