Name	Info	Provider	Link
	free resource	Medknow Publications and Media Pvt Ltd	http://www.thoracicmedicine.org/article.asp?issn=1817-1737;year=2010;volume=5;issue=4;spage=201;epage=216;aulast=Allen
	subscription/membership/fee required	Ovid Technologies, Inc.	http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=20981180.ui
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20981180/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/20981180