Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=21824002.ui
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21824002/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/21824002
	subscription/membership/fee required	De Gruyter	https://www.degruyter.com/document/doi/10.1515/BC.2011.086