Name Info Provider Link
subscription/membership/fee required Atypon https://journals.physiology.org/doi/10.1152/ajpendo.1988.254.5.E639?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub 0pubmed
Vitamin D Deficiency free resource MedlinePlus Health Information https://medlineplus.gov/vitaminddeficiency.html