1. G. V. Dedkov and A. A. Kyasov, Fiz. Tverd. Tela (St. Petersburg) 44(10), 1729 (2002) [Phys. Solid State 44 (10), 1809 (2002)].
2. G. V. Dedkov and A. A. Kyasov, Fiz. Tverd. Tela (St. Petersburg) 51(1), 3 (2009) [Phys. Solid State 51 (1), 1 (2009)].
3. V. I. Kesaev and I. N. Maliev, Vladikavkaz. Mat. Zh. 11, 11 (2009).
4. E. Jahnke, F. Emde, and F. Lösch, Tafeln höherer Funktionen (Teubner, Stuttgart, 1966; Nauka, Moscow, 1977) [in German and in Russian].
5. G. V. Dedkov and A. A. Kyasov, Fiz. Tverd. Tela (St. Petersburg) 43(1), 169 (2001) [Phys. Solid State 43 (1), 176 (2001)].