NIEDERLE, Jiří, NIKITIN, A. Extended SUSY with central charges in quantum mechanics. In: NIKITIN, A.G., BOYKO, V.M., POPOVYCH, R.O., eds. Proceedings of Fourth International Conferene "Symmetry in Nonlinear Mathematical Physics". Vol. 2. Kiev: Institute of Mathematics of NAS of Ukraine, 2002, s. 497-507. Proceedings of Institute of Mathematics of NAS of Ukraine., 43. ISBN 966-02-2487-7.