Vittek, Jan, Juraj Altus, Bernard Bednarik, Rastislav Tabacek, Stephen J. Dodds, and Roy Perryman. 2001. “Research of New Sensorless Speed Controlled Drives With Induction Motors for Traction Applications”. Communications - Scientific Letters of the University of Zilina 3 (2-3), 5-15. http://journals.uniza.sk/index.php/communications/article/view/1436.