Warning message Node revision 628 not found in node Upper and low bounds of azimuthal numbers related to elementary wave functions of an elliptic cylinder . Perharps it was deleted. Node revision 508 not found in node Mechanical properties study for graphene sheets of various size . Perharps it was deleted. Chumachenko A. N. Николаевич RussiaSaratov Saratov State University, Russia, Saratov, Astrakhanskaya 83 rector@sgu.ru Author's articles 18th International Saratov Winter School “Contemporary Problems of Function Theory and Their Applications” 19th International Saratov Winter School “Contemporary Problems of Function Theory and Their Applications“