1. Winkler, L. W.: Arch. Pharm. Ber. Dtsch. Pharm. Ges., 266, 45–62 (1928).
2. Sekiguchi, T. and Tanaka, M.: Jpn. Kokai Tokkyo Koho JP 60,185,743 [85,185,743] (1985);
3. Chem. Abstr., 104, 68598x (1986).
4. Finaru, A.; Cascaval, A.; Tudorache, E. and Prisecaru, M.: Rev. Chim. (Bucharest), 50 (1) 8???12 (1999);
5. Chem. Abstr., 131, 170145s (1999).