1. Fishering National Service of Chile (SERNAP), Ministerio de Economía Fomento y Reconstrucción, Anuario Estadístico, 1989.
2. WHO, Report of a WHO Committee, Techn. Rep. Ser., 1985, p. 718.
3. K. HEYDORN, Neutron Activation Analysis for Clinical Trace Element Research, Vols 1 and 3, CRC Press, USA, 1984.
4. D. DE SOETE, R. GIJBELS, J. HOSTE, Neutron Activation Analysis, Wiley Interscience, London, 1972.
5. J. R. MOODY, Anal. Chem., 54 (1982) 1358A.