by MARKOV, LJUBEN I, KISAOV, VESELIN D, KHRISTOVA, IRENA G, BORSHUKOV, DOBRIN G, MILANOVA, TONJA G, KALCHEV, STOJAN V
Year of Publication 15.10.1990

by RADEV, IVAN S, POPOVA, DONKA V, KANCHEV, TODOR TS, BORSHUKOV, DOBRIN G, MILANOVA, TONJA G, VAPTSAROV, NIKOLAJ I, IVANOVA, LJUDMILA S, ARABADZHIJSKI, KRASTJU S
Year of Publication 14.07.1989

by TURLAKOV,HRISTO A.,BG, BARBUTOV,VENELIN G.,BG, HRISTOVA,IRENA G.,BG, BORSHUKOV,DOBRIN G.,BG, KOKALITCHEV,NIKOLAY K.,BG
Year of Publication 08.05.1991

by BARBUTOV,VENELIN G.,BG, TURLAKOV,KHRISTO A.,BG, BORSHUKOV,DOBRIN G.,BG, KHRISTOVA,IRENA G.,BG, KOKALICHEV,NIKOLAJJ K.,BG
Year of Publication 15.03.1989