Name	Info	Provider	Link
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22263177/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/22263177
	free resource	Inforang	http://www.jchestsurg.org/journal/view.html?doi=10.5090/kjtcs.2011.44.4.307