1. K. V. Nikonorov, É. A. Gurylev, and F. F. Mertsalova, Izv. Akad. Nauk SSSR, Ser. Khim., 1159 (1970).
2. F. M. Kharrasova and G. Kamai, Zh. Obshch. Khim.,34, 2195 (1964).
3. M. Grayson and E. J. Griffith, Topics in Phosphorus Chemistry, Vol. 5, Wiley, New York-London-Sydney (1967), p. 293.
4. A. E. Arbuzov, Zh. Russk. Fiz.-Khim. Ova.,42, 549 (1910).
5. E. A. Krasil'nikova, Uspekhi Khimii, Vol. 56, p. 1638 (1977).