Name	Info	Provider	Link
	free resource	BioMed Central	https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-019-7414-9
Flu	free resource	MedlinePlus Health Information	https://medlineplus.gov/flu.html
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/31409397/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/31409397
Full text from	free resource	Diposit Digital de la Universitat de Barcelona	http://hdl.handle.net/2445/151349