Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=15918548.ui
	subscription/membership/fee required	Springer	https://www.springerlink.com/openurl.asp?genre=article&issn=0885-7490&volume=20&issue=1&spage=35