1. N. K. Kochetkov, A. Ya. Khorlin, and V. E. Vas'kovskii, ?Triterpene saponins,? Izv. Akad. Nauk SSSR, Ser. Khim., 1398 (1963).
2. W. Winkler and P. Patt, Naturwissenschaften,47, No. 4, 83 (1904).
3. M. T. Turakhozhaev, M. R. I. Shamsutdinov, and T. T. Shakirov, in: Abstracts of Lectures at an All-Union Conference on Ion Exchange [in Russian], Moscow, (1979), p. 233.
4. L. A. Yavich, in: The Use of Ion-Exchange and Extraction Methods in the Production of Biologically Active Substances [in Russian], Tbilisi (1979), p. 98.
5. L. A. Yavich, Soobshch. Akad. Nauk GSSR, No. 3, p. 91, 625 (1978).