Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=16283536.ui
	subscription/membership/fee required	Springer	https://www.springerlink.com/openurl.asp?genre=article&issn=1567-567X&volume=32&issue=2&spage=161