Martincek, I., I. Turek, M. Dado, K. Grondzak, and S. Cernicky. “Intermodal Interference in Optical Fibres”. Communications - Scientific Letters of the University of Zilina, Vol. 2, no. 2, June 2000, pp. 4-9, http://journals.uniza.sk/index.php/communications/article/view/1050.