[1] E. M. Ashraf, H. A. Khater and A. L. Sewaidan, “Radiation Exposure Due to Agricultural Uses of Phosphate Fertilizers,” Radiation Measurements, Vol. 43, No. 8, 2008, pp. 1402-1407.
http://dx.doi.org/10.1016/j.radmeas.2008.04.084
[2] P. M. Rutherford, M. J. Dudas and J. M. Arocena, “Radio-Activity and Elemental Composition of Phosphogypsum Produced from Three Phosphate Rock Sources,” Waste Management & Research, Vol. 13, No. 5, 1995, pp. 407-423.
[3] H. Beddow, S. Black and D. Read, “Naturally Occurring Radioactive Material (NORM) from a Former Phosphoric Acid Processing Plant,” Journal of Environmental Radioactivity, Vol. 86, No. 3, 2006, pp. 289-312.
http://dx.doi.org/10.1016/j.jenvrad.2005.09.006
[4] I. Othman and M. S. Al-Masri, “Impact of Phosphate Industry on the Environment: A Case Study,” Applied Radiation and Isotopes, Vol. 65, No. 1, 2007, pp. 131-141.
http://dx.doi.org/10.1016/j.apradiso.2006.06.014
[5] N. Casacuberta, P. Masqué and J. Garcia-Orellana, “Fluxes of 238U Decay Series Radionuclides in a Dicalcium Phosphate Industrial Plant,” Journal of Hazardous Materials, Vol. 190, No. 1-3, 2011, pp. 245-252.
http://dx.doi.org/10.1016/j.jhazmat.2011.03.035
[6] J. R. Silva, “Caracterizacao Hidrogeologica da Jazida de Itataia,” M.Sc. Dissertation, Universidade Federal do Ceara, Ceara, 2003, p. 126.
[7] National Commission for Nuclear Energy—CNEN, Standard CNEN-NN-4.01, “Requisitos de Seguranca e Protecao Radiologica para Instalacoes Minero-Industriais,” 2005, p. 19.
[8] National Commission for Nuclear Energy—CNEN, Standard CNEN-NN-3.01, “Diretrizes Basicas de Protecao Radiologica,” 2005a, p. 34.
[9] National Commission for Nuclear Energy—CNEN, “Standard Posicao Regulatoria 3.01/008:2011 Programa de Monitoracao Radiologica Ambiental,” 2011, p. 5.
[10] National Commission for Nuclear Energy—CNEN, “Standard Posicao Regulatoria 3.01/009:2011 Modelo para Elaboracao de Relatorios de Programa de Monitoracao Radiologica Ambiental,” 2011, p. 5.
[11] M. Garcia-Talavera, J. L. M. Matarranz, R. Salas and L. Ramos, “A Regulatory Perspective on the Radiological Impact of NORM Industries: The Case of the Spanish Phosphate Industry,” Journal of Environmental Radioactivity, Vol. 102, No. 1, 2011, pp. 1-7.
http://dx.doi.org/10.1016/j.jenvrad.2010.08.007
[12] A. J. Ceteno, “Curso de Estatistica Aplicada a Biologia,” Universidade Federal de Goias, Goiania, 1999, p. 188.
[13] H. G. Arango, “Bioestatistica: Teorica e Computacional Com Bancos de Dados Reais em Disco,” 3rd Edition, Guanabara & Koogan, 2009, p. 438.
[14] M. A. Schork and R. D. Remington, “Statistics with Applications to the Biological and Health Science,” 3rd Edition, Prentice Hall, Upper Saddle River, 2000, p. 478.
[15] B. Rosner, “Fundamentals of Biostatistics,” 5th Edition, Duxbury Thomson Learning, Stamford, 2000, p. 792.
[16] D. F. Ferreira, “Estatistica Multivariada,” Editora da UFLA, Lavras, 2008, p. 650 p.
[17] J. L. Valentin, “Ecologia Numérica. Uma Introducao a Analise Multivariada de Dados Ecologicos,” Interciência, Rio de Janeiro, 2000, p. 117.
[18] N. J. Gotelli and A. M. Ellison, “A Primer of Ecological Statistic,” Sinauer Associates, Sunderland, 2004, p. 510.
[19] J. M. Godoy, D. C. Lauria, M. L. D. P. Godoy and R. P. Cunha, “Development of a Sequential Method for Determination of 238U, 234U, 232Th, 230Th, 228Th, 228Ra, 226Ra and 210Pb in Environmental Samples,” Journal of Radio-Analytical Nuclear Chemistry, Vol. 182, No. 1, 1994, pp. 165-169. http://dx.doi.org/10.1007/BF02047980