"A Potentiometric study of the humic acids derived from coal. "; "Brown, C. F.", "Collett, Armand René, 1895-"; "Humic acid.", "Coal--Analysis."; "Brown, C. F.", "Collett, Armand René, 1895-"; "1938"; "Journal article reprint from: Fuel in Science and Practice, v.17:no.12 (1938). "; ""; "P1224"; "pec"; "Humic acid.", "Coal--Analysis."; "14256"; .