by STAMENOV,RUMEN V, RAJJCHEV,RUMEN M, ALEKSANDROV,ALEKSANDR L, CANKOV,VALENTIN K, MAZGALOVA,ZORNICA G
Year of Publication 14.08.1987

by PRIKHNO GENNADIJ M,SU, ALEKSANDROV ALEKSANDR L,SU, TRUSHLYAKOV SERGEJ A,SU, KRIVOSHEJ NIKOLAJ V,SU
Year of Publication 30.03.1993

by SEMERDZHIEV,ATANAS KH, GEORGIEVA,ADRIANA R, SAVOV,GRIGOR G, KHRISTOVA,IRENA G, NEJJCHEV,SLAVEJJKO K, RAJJCHEV,RUMEN M, ALEKSANDROV,ALEKSANDR L, FILOV,KAMEN V, TODOROV,DIMITR T, MAZGALOVA,ZORNICA G, MOROZOV,JULIJJ N, PEEV,RUMEN M
Year of Publication 14.06.1985