1. P. A. Akishin, V. A. Naumov, and V. M. Tatevskii,Kristallografiya,4, No. 2, 194–200 (1959).
2. P. A. Petrov, S. V. Nedyak, and A. A. Maltsev,Vestn. Mosk. Gos. Univ., Ser. Khim.,16, No. 3, 281–283 (1975).
3. Yu. S. Ezhov and S. A. Komarov,Zh. Strukt. Khim.,26, No. 6, 60–64 (1985).
4. M. V. Popik, S. V. Sokolov, A. V. Golubinskii, et al., in:Structure and Properties of Molecules [in Russian], K. S. Krasnov (ed.), IKhTI, Ivanovo (1988), pp. 84–93.
5. M. V. Popik, M. A. Tafipolskii, S. Samdal, et al.,Kristallografiya,39, No. 2, 291–300 (1994).