Name	Info	Provider	Link
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=38181816.ui
	free resource	Georg Thieme Verlag Stuttgart, New York	http://www.thieme-connect.com/DOI/DOI?10.1055/s-0043-1778106