1. T. R. Akopyan, E. G. Paronikyan, T. P. Sarkisyan, et al., Arm. Khim. Zh., No. 9, 716–719 (1979).
2. S. A. Vartanyan, T. R. Akopyan, and E. G. Paronikyan, Ibid., 720–722.
3. V. M. Bunin and V. E. Anisimov (editors), Vitamin U (S-methylmethionine). Nature, Properties, and Uses [in Russian], Moscow (1973), pp. 94–95.
4. M. G. Voronkov, V. I. Knutov, V. A. Usov, et al., Khim. Geterotsikl. Soedin., No. 11, 1474–1475 (1979).
5. M. G. Voronkov and V. I. Knutov, Uspekhi Khimii,51, No. 9, 1484–1551 (1982).