https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-52732000000200003
https://www.scielo.br/pdf/rbgg/v19n1/pt_1809-9823-rbgg-19-01-00153.pdf
https://www.scielo.br/pdf/rbcp/v28n1/08.pdf
http://ve.scielo.org/scielo.php?script=sci_arttext&pid=S0004-06222007000300002
