Name	Info	Provider	Link
	subscription/membership/fee required	Ingenta plc	https://www.ingentaconnect.com/openurl?genre=article&issn=&volume=44&issue=3&spage=e816&aulast=Singh
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=34966095.ui
	subscription/membership/fee required	Wolters Kluwer	https://doi.org/10.1097/MPH.0000000000002380