This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
S. A. Plaksa
Department of complex analysis and potential theory, Institute of Mathematics of the National Academy of Sciences of Ukraine, 3 Tereshchenkivska Street, Kiev, Ukraine
R. P. Pukhtaievych
Department of complex analysis and potential theory, Institute of Mathematics of the National Academy of Sciences of Ukraine, 3 Tereshchenkivska Street, Kiev, Ukraine