1. D. Y. Graham,N. Engl. J. Med., No.23, 1314 - 1317 (1977).
2. P. G. Lankisch and W. Creutzfeldt,Clin. Gastroenterol.,13(3), 985 - 999 (1984).
3. A. Pap and V. Varro,Hepatogastroenterol.,31(1), 47 - 51 (1984).
4. O. A. Belyaev, D. V. Chizhikov, and G. A. Mikhailets,Khim.- Farm. Zh.,20(8), 1014 - 1015 (1986).
5. O. A. Belyaev and G. E. Grinberg,Khim.-Farm. Zh.,26(2), 40 - 41 (1992).