1. D. F. Marchidan andM. Ciopec, Rev. Roumaine Chim., 16 (1971) 1145.
2. D. I. Marchidan, M. Ciopec andAl. Birhala, Rev. Chim., Bucharest, 27 (1976) 394.
3. M. Ciopec andD. I. Marchidan, Rev. Roumaine Chim., 17 (1972) 1139.
4. Handbook of Chemistry and Physics, CRC-Press, Cleveland, 1975, p. 127.
5. Lange's Handbook of Chemistry, McGraw-Hill Book Company, New York 1967, p. 347.