T. J. . Souza, M. C. C. de . Amorim, J. A. da S. Neto, and E. F. N. . Santos, “Perception of the regulars of Permanent Preservation Area in Petrolina-PE as the environment and environmental degradation”, RSDV, vol. 2, no. 3, pp. 317–325, Dec. 2012.