1. S. V. Skobeleva, A. N. Egorochkin, V. L. Tsvetkova, N. E. Tyulina, N. P. Erchak, and É. Lukevits, Izv. Akad. Nauk Latv. SSR, Ser. Khim., No. 3, 355 (1988).
2. A. N. Egorochkin, é. Lukevits, and M. G. Voronkov, Khim. Geterotsikl. Soedin., No. 4, 499 (1965).
3. é. Lukevits, N. P. Erchak, Yu. Yu. Popelis, and R. M. Zolotoyabko, The Chemistry of Heteroorganic Compounds [in Russian], Nauka, Leningrad (1976), p. 63.
4. D. Doddrell, K. G. Lewis, C. E. Mulquiney, W. Adcock, W. Kitching, and M. Bullpitt, Aust. J. Chem. 27, 417 (1974).
5. M. MÄgi, E. Lippmaa, E. Lukevics, and N. P. Jercak, Org. Magn. Reson. 9, 299 (1977).