1. Especiación de elementos metálicos en suelos y su influencia sobre la asimilación por plantas;Barona,1994
2. Extraction of metals from soils and sewage sludges by refluxing with aqua regia;Berrow;Analyst,1983
3. Mobility of heavy metals in pine forest soil as influenced by experimental acidification;Berthelsen;Water, Air Soil Pollut.,1994
4. Methods for chemical analysis of soil;Blakemore;New Zealand Soil Bureau, Scientific Report 10A,1977
5. Some experiments on extraction of heavy metals present in soil;Calvet;Intern. J. Environ. Anal. Chem.,1990