1. Guidelines for data acquisition and data quality evaluation in environmental chemistry;American Chemical Society;Anal. Chem.,1980
2. Food and Nutrition Board,1980
3. Contenido de plomo en conservas vegetales;Catalá;Rev. Agroquim. Tecnol. Alimment.,1977
4. Distribution of cadmium and zinc/cadmium ratios in crops from 19 states east of the Rocky Mountains;Huffman;J. Environ. Qual.,1973
5. Encuesta de presupuestos familiares;Instituto Nacional de Estadística,1985