1. R. A. Gavars, J. P. Stradyn, and S. A. Giller, Izv. Akad. Nauk LatvSSR, Ser. Khim., No. 3, 381 (1964).
2. R. A. Gavars, J. P. Stradyn, and S. A. Giller, Dokl. Akad. Nauk SSSR,157, 381 (1964).
3. A. E. C. Lucken, J. Chem. Soc. A, 991 (1966).
4. Landolt-Börnstein. Numerical Data and Functional Relationships in Science and Technology. New Series [in German], Group 2 (1980); Vol. 9, Pt. d1, p. 572.
5. Landolt-Börnstein. Numerical Data and Functional Relationships in Science and Technology. New Series [in German], Group 2 (1988); Vol. 17, Pt. f, p. 277.