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2. Commission of the European Communities. (1990). Intercomparison of Environmental Gamma Dose Rate Meters, Part I, 1984 and 1985 Experiments. Organized by the Radiation Protection Division, Luxembourg (pp. 72).
3. A study of natural radioactivity in Brazil;Cullen,1965
4. Instituto Brasileiro de Geografia e Estatística—IBGE. (2000). http://www.ibge.gov.br.
5. Instituto Brasileiro de Geografia e Estatística—IBGE. (1959) Enciclopédia dos Municípios Brasileiros (pp. 87–91).