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2. N. V. Solov'eva and I. N. Garkina, Vitamin B15 (Pangamic Acid) [in Russian], Moscow (1965), p. 28.
3. A. M. Yurkevich, V. N. Rekunova, O. N. Khandozhko, and N. A. Preobrazhenskii, Synthesis of Natural Compounds, Their Analogs and Fragments [in Russian], Moscow-Leningrad (1965), p. 146.
4. T. Wieland and D. Seiber, Naturwissenschaften,40, 242 (1953).
5. R. A. Ray and R. B. Johnston, J. Med. Chem.,8(2), 275 (1965); Ref. Zh., “Khimiya,” No. HZh564 (1966).