Name	Info	Provider	Link
	subscription/membership/fee required	Ediciones Doyma, S.L.	http://www.elsevier.es/en/linksolver/ft/pii/S0009-739X(20)30193-7
	subscription/membership/fee required	Elsevier Science	https://linkinghub.elsevier.com/retrieve/pii/S0009-739X(20)30193-7
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/34629484/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/34629484