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2. L. Mond and C. Langer, British Patent 12 (1988) p. 608.
3. BASF, Badische Anilin and Soda Fabrik. Patents: EP 21151/1911; GP 254571/1911; 256296/1911; 259870/1911; 265295/1912.
4. C. Bosch and W. Wild, Canadian Patent 153 (1914) p. 379.