Name	Info	Provider	Link
	subscription/membership/fee required	Elsevier Science	https://linkinghub.elsevier.com/retrieve/pii/0006-2952(91)90265-7
Iron	free resource	MedlinePlus Health Information	https://medlineplus.gov/iron.html
Cited by Patents in	free resource	The Lens - Patent Citations Database	https://www.lens.org/lens/search/patent/list?q=reference_cited.nlp.ids.pmid:1909528