1. O. A. Kudasheva and N. V. Sevryugova, Akust. Zh. 22, 385 (1976).
2. I. V. Vovk, Akust. Zh. 26, 522 (1980).
3. A. G. Kyurkchan, Radiotekh. Elektron. (Moscow) 44 (7), 787 (1999).
4. I. V. Vovk, Akust. Zh. 32, 378 (1985).
5. V. P. Shestopalov, Method of Riman-Hylbery Problem in Theory of Diffraction and Electromagnetic Wave Propagation (KhGU, Kharkov, 1971) [in Russian].