1. Jaffray, J., Comp. rend. 1346, 224 (1947).
2. Vol’fkovich, S.I., et al., Izvest, Akad. Nauk SSSR., Otdel Khim, Nauk. 209, (1954).
3. Vol’nova, V.A., Akad. Nauk SSSR, 121, (1955).
4. Kato, C., Yogyo Kyokai Shi, 243, 67, (1959).
5. Reisman, A., Anal. Chem. 1566, 32, (1960).