The present paper is devoted to the 70 th Anniversary of the Editor-in-Chiefof ”Izvestiya of Saratov University. New Series. Series: Mathematics. Mechanics. Informatics”, DSc (Physics & Mathematics), Prof., Head of the Department of Mathematical Theory of Elasticity and Biomechanics, a Laureate of the State Prize of the Russian Federation in the field of science and technology Leonid Yu. Kossovich.