1. The chemical nature of the carboxyl groups of humic acids and conversion of humic acids to ammonium nitrohumates;Schwartz;Fuel,1965
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3. Action of nitric acid on lignites mathematical models 2. Nitrogen forms;Moliner;Fuel,1983
4. Lignite-based nitrogenous fertilisers;Baris;Energy Sources,1983
5. Production and use of coal fertilizers;Mazumdar;Fuel Res. Inst. (India) News,1976