1. Perkin, A. G.: Ref. Chem. Abstr.1906, 1433.
2. Hattori, S., u.M. Hasegawa: Ref. Chem. Abstr.34, 3740 (1940).
3. Nakabayashi, T.: Ref. Chem. Abstr.48, 5942 (1954).
4. King, F. E., u.R. M. Acheson: J. Chem. Soc. [London]168 (1950).
5. Nordal, A., u.D. Oiseth: Pharmaz. Acta Helv.32, 114 (1957).