Regular attractors and nonautonomous perturbations of them Marko I Vishik, Sergey V Zelik and Vladimir V Chepyzhov Sbornik : Mathematics (1064-5616) 2013 vol.204 no.1 pp.1- http://iopscience.iop.org/1064-5616/204/1 A family of Nikishin systems with periodic recurrence coefficients Steven Delvaux, Abey Lopez and Guillermo L Lopez Sbornik : Mathematics (1064-5616) 2013 vol.204 no.1 pp.43- http://i..