https://www.google.com/url?q=http://www.teses.usp.br/teses/disponiveis/3/3144/tde-11082010-171812/publico/Tese_Macksuel_Soares_de_Azevedo.pdf&sa=U&ved=0ahUKEwjpob3jzPTeAhWEiJAKHRaeCQIQFggFMAA&client=internal-uds-cse&cx=011662445380875560067:cack5lsxley&usg=AOvVaw1zoBrqbf3TloPwPRkWvAAx