P. MICHELBERGER, P. VÁRLAKI, B. SÁLYI, J. KOZMA, and I. MAGYAR, “SOME ACTUAL PROBLEMS OF MEDIUM-TERM TECHNOLOGICAL DEVELOPMENT STRATEGY IN THE HUNGARIAN BUS INDUSTRY ”, Period. Polytech. Transp. Eng., vol. 12, no. 1-2, pp. 59–72, Jan. 1984.