1. M. A. Mikhaleva and V. P. Mamaev, Izv. SO AN SSSR, 1968 (in press).
2. V. P. Mamaev and E. A. Gracheva, KhGS [Chemistry of Heterocyclic Compounds], 4, 516, 1968.
3. Yu. K. Yur'ev, Practical Work in Organic Chemistry, Nos. I and II [in Russian], Izd. MGU p. 211, 1961.
4. O. Jardetzky, P. Pappas, and N. G. Wade, J. Am. Chem. Soc., 85, 1657, 1963.
5. H. H. Hatt, and A. C. K. Triffett, Chem. Communic., 439, 1965.