G. Berkenbrock, C. Hirata, F. de Oliveira Júnior, and J. de Oliveira. IT Revolutions, volume 11 of Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, page 161-170. Springer, (2008)
W. de Oliveira Junior. Federal University of Pernambuco, Recife, Brazil, (2004)ndltd.org (oai:agregador.ibict.br.BDTD_UFPE:oai:repositorio.ufpe.br:123456789/1970).