Name	Info	Provider	Link
	free resource	Medknow Publications and Media Pvt Ltd	http://www.clinicalimagingscience.org/article.asp?issn=2156-7514;year=2011;volume=1;issue=1;spage=5;epage=5;aulast=Alvarez
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21915386/
	free resource	Europe PubMed Central	https://europepmc.org/abstract/MED/21915386