Name	Info	Provider	Link
	free resource	PubMed Central	https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/12920477/
	free resource	Scientific Electronic Library Online	https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802003000300010&lng=en&nrm=iso&tlng=en