1. N. A. Vol'kenau, in: Methods of Heteroorganic Chemistry [in Russian], edited by A. N. Nesmeyanov and K. A. Kocheshkov, Nauka, Moscow (1976), p. 150.
2. K. H. Pannell, B. L. Kalsotra, and C. Parkanyi, J. Heterocycl. Chem., 15, 1057 (1978).
3. W. Siebert, Adv. Organomet. Chem., 18, 301 (1980).
4. E. O. Fischer and K. Ofele, Chem. Ber., 91, 2395 (1958).
5. K. K. Joshi and P. L. Pauson, Proc. Chem. Soc., No. 10, 326 (1962).