Izvoltova, J., P. Pisca, A. Villim, and M. Mancovic. “Precision Analysis of Height Measurements Realized on Ballastless Track”. Communications - Scientific Letters of the University of Zilina, Vol. 16, no. 4, Dec. 2014, pp. 63-67, http://journals.uniza.sk/index.php/communications/article/view/578.