Name	Info	Provider	Link
	subscription/membership/fee required	Elsevier Science	https://linkinghub.elsevier.com/retrieve/pii/S0886335001011282
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=11973103.ui
	subscription/membership/fee required	Wolters Kluwer	https://doi.org/10.1016/s0886-3350(01)01128-2