1. L. P. Sidorova and N. P. Bednyagina, Khim. Geterotsikl. Soedin., 1138 (1972).
2. G. Hayasi and K. Maeda, Kagaku-no Reiki,22, No. 1, 1 (1968).
3. I. Hausser, D. Jerhel, and K. Kuhn, Ber.,84, 651 (1951).
4. N. P. Bednyagina, G. N. Lipunova, and G.A. Mokrushina, USSR Author's Certificate No. 241,442 (1969);
5. Byul. Izobr., No. 14, 23 (1969).