Name	Info	Provider	Link
	subscription/membership/fee required	Ingenta plc	https://www.ingentaconnect.com/openurl?genre=article&issn=&volume=276&issue=6&spage=e976&aulast=Purcell
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=34183507.ui
	subscription/membership/fee required	Wolters Kluwer	https://doi.org/10.1097/SLA.0000000000005034