CENTER for ECOLOGICAL RESEARCH, KYOTO UNIV.: Unpublished data.
FUJINAGA, T. and T. HORI (1982) : Biwa-ko no kankyo kagaku. [Environmental chemistry of lake Biwa]. The Japan Society for Promotion of Sciences, Tokyo (in Japanese).
HAYES, M. H. B. (1985) : Extraction of humic substances from soil. In Humic substances in soil, sediment, and water. - Geochemistry, isolation, and characterization - G. R. AIKEN, D. M. MCKNIGHT, R. L. WERSHAW, and P. MACCARTHY (ed.) : 329-362. Wiley-Intersci., New York.