MÖSSBAUER SPECTROSCOPIC STUDIES OF HUMIC ACID AND FULVIC ACID SOIL FRACTIONS D.P.E. Dickson, L. Heller-Kallai et I. Rozenson J. Phys. Colloques, 41 C1 (1980) C1-409-C1-410 DOI: 10.1051/jphyscol:19801158