Gavrilovic, B. S. “Simulation of Torsion Moment at the Wheel Set of the Railway Vehicle With the Traction Electromotor for Wavy Direct Current”. Communications - Scientific Letters of the University of Zilina, Vol. 10, no. 3, Sept. 2008, pp. 5-9, http://journals.uniza.sk/index.php/communications/article/view/1083.