Institution: | (1) Department of Mathematics, Indiana University, Bloomington, IN-47405, USA;(2) South Ural State University, Leninskii pr. 76, Chelyabinsk, 454080, Russia;(3) Laboratoire Paul Painlévé, U.F.R. de Mathématique, Université des Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq Cedex, France |