1. Celap, M. B., T. J. Janjic, and D. Radanovic: Glasnik Hem. Drustva, Beograd 28, 19–25 (1963).
2. Cerny, P., and J. Kubin: Acta Fac. Rer. Nat. Univ. Comenianae Chimia 4, 667 (1960).
3. Hayashi, S., and K. Kotsuji: Japan Analyst 10, 392 (1961); cf. Z. Anal. Chem. 193, 135 (1963).
4. Kulaev, F. N.: Ž. Anal. Chim. 13, 172 (1958); cf. Z. Anal. Chem. 165, 441 (1959).
5. Labii, Yu. M.: Ukrain. Chim. Ž. 28, 641 (1962).