Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=11504883.ui
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/11504883/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/11504883
	subscription/membership/fee required	Silverchair Information Systems	https://academic.oup.com/nar/article-lookup/doi/10.1093/nar/29.16.3448