BRAUN, Jaromír, BERKA, Zbyněk, ŽILKA, Zdeněk. The general conditions of realization and approximation of a group delay characteristic. Brno: Institute of Radio Electronics, Brno University of Technology, 1999. ISBN 80-214-1327-1. In: SVAČINA, J., ed. Radioelektronika'99. , s. 21-24.