T. Dumitriu, M. Culea, M. Nichita, and T. Munteanu, “Non-conventional method for friction compensation in DC drive position tracking”, The Annals of “Dunarea de Jos“ University of Galati. Fascicle III, Electrotechnics, Electronics, Automatic Control, Informatics, vol. 29, pp. 106-109, Dec. 2006.