1. M. I. Eides, H. Grotch, and V. A. Shelyuto, Phys. Rep. 342, 63 (2001).
2. N. A. Boikova, S. V. Kleshchevskaya, Yu. N. Tyukhtyaev, and R. N. Faustov, Teor. Mat. Fiz. 149, 325 (2006) [Theor.Math. Phys. 149, 1578 (2006)].
3. V. V. Dvoeglazov, Yu. N. Tyukhtyaev, and R. N. Faustov, Fiz. Élem.Chastits At. Yadra 25, 144 (1994) [Phys. Part. Nucl. 25, 58 (1994)].
4. N. A. Boikova, S. V. Kleshchevskaya, Yu. N. Tyukhtyaev, and R. N. Faustov, Yad. Fiz. 72, 300 (2009) [Phys. At. Nucl. 72, 272 (2009)].
5. R. N. Fell, Preprint BUW-01742 (Wuppertal, 1992).