Elemental composition of humic and fulvic acids in the epipedon of some Estonian solidsReintam, Loit; Kann, Jüri; Kailas, Tiiu; Kährik, RajaProceedings of the Estonian Academy of Sciences. Chemistry2000 / 3, p. 131-144 https://artiklid.elnet.ee/record=b2397615*est