Nonlinear Dynamics and Systems Theory. An International Journal of Research and Surveys (Nonlinear Dyn. Syst. Theory) (20060101), 6, no.~2, 205-210. ISSN: 1562-8353 (print).eISSN: 1813-7385.
Nonlinear Dynamics and Systems Theory. An International Journal of Research and Surveys (Nonlinear Dyn. Syst. Theory) (20040101), 4, no.~1, 115-124. ISSN: 1562-8353 (print).eISSN: 1813-7385.