Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=17149046.ui
	subscription/membership/fee required	Wolters Kluwer	https://dx.doi.org/10.1097/00124645-200611000-00005