SOME PROBLEMS FOR SOBOLEV SPACES ON THE HALF-LINE Статья Kalyabin G.A. Proceedings of the Steklov Institute of Mathematics. Том 255. 2006. С. 150-158
ON THE STABILITY OF THE INDEX OF UNBOUNDED NONLOCAL OPERATORS IN SOBOLEV SPACES Статья Gurevich P.L. Proceedings of the Steklov Institute of Mathematics. Том 255. 2006. С. 108-126