Name	Info	Provider	Link
Vitamin A	free resource	MedlinePlus Health Information	https://medlineplus.gov/vitamina.html
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=22370147.ui
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22370147/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/22370147
	free resource	Cambridge University Press	http://journals.cambridge.org/abstract_S0007114512000128