Nonlinear analysis of EEG in chess players Pawel Stepien, Wlodzimierz Klonowski and Nikolay Suvorov EPJ Nonlinear Biomed Phys, 3 1 (2015) 1 Published online: 12 March 2015 DOI: 10.1140/epjnbp/s40366-015-0016-2