Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=708619.ui
	subscription/membership/fee required	Wiley	https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0007-0963&date=1978&volume=99&issue=4&spage=455
	subscription/membership/fee required	Silverchair Information Systems	https://academic.oup.com/bjd/article-lookup/doi/10.1111/j.1365-2133.1978.tb06188.x