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2. ?Method for the Reduction of the Concentration of NO in Combustion Effluents Using Ammonia?, U.S. Patent 3,900,554 (1975).
3. Thermal DeNOx Controlling nitrogen oxides emissions by a noncatalytic process
4. and ?Urea Reduction of NOx in Combustion Effluents,? U.S. Patent 4,208,386 (1982).
5. and ?Urea Reduction of NOx in Fuel Rich Combustion Effluents,? U.S. Patent 4,325,924 (1982).