L. Kiss, L. Z. Rácz, O. P. Geszti, I. Horváth, and J. Somló, “THERMAL GENERATING UNIT TRANSIENTS FOLLOWING STEP-CHANGES OF FREQUENCY ("FREQUENCY STEPS") ”, Period. Polytech. Elec. Eng., vol. 17, no. 3, pp. 225–254, Jan. 1973.