Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=21875393.ui
	subscription/membership/fee required	De Gruyter	https://www.degruyter.com/document/doi/10.1515/CCLM.2011.680