1. US Patent no. 3 719 683, 1973; Ref. Zh., Khim., 1974, no. 5 N 372 P; US Patent no. 4 152 434, 1979; Ref. Zh., Khim., 1979, no. 15 O 195 P.
2. US Patent no. 4 195 088, 1980; Ref. Zh., Khim., 1980, no. 23 O 343 P.
3. US Patent no. 3 819 640, 1974; Ref. Zh., Khim., 1976, no. 3 O 159 P; El-Gendy, M.A., Farag, H.H., Ahmed, A.N., Stedman, J.R., and Alkaramany, G.S., Bull. Pharm. Sci., Assiut Univ., 1992, vol. 15, p. 9; Ebeid, M.Y., Abou, T., Nageh, A., Lashine, S.M., El-Shanawany, A.A., and Abou, K.M., Zagazig J. Pharm. Sci., 1993, vol. 2, p. 129; US Patent no. 444 341, 1979; Ref. Zh., Khim., 1980, no. 2 O 148 P; US Patent no. 4 059 584, 1977; Ref. Zh., Khim., 1978, no. 17 O 174 P.
4. Cundy, D.J., Holan, G., and Otaegui, M., Bioorg. Med. Chem. Lett. 1997, vol. 7, p. 669.
5. UK Patent no. 1 213 796, 1970; Ref. Zh., Khim., 1971, no. 13 N 684 P.