Name	Info	Provider	Link
	subscription/membership/fee required	Ingenta plc	https://www.ingentaconnect.com/openurl?genre=article&issn=1077-4114&volume=46&issue=6&spage=e457&aulast=Principe
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=38934620.ui
	subscription/membership/fee required	Wolters Kluwer	https://doi.org/10.1097/MPH.0000000000002901