by MIKHAJJLOV,DIMO G, KIRCHEVA,RADKA S, GRIGOROV,GRIGOR R, ATANASOV,KRASIMIR M, DENEVA,TEMENUZHKA D, PETKOV,LAZAR I
Year of Publication 15.01.1985

by MAKHOVA,LILJANA D, MIKHAJJLOV,DIMO G, KIRCHEVA,RADKA S, ATANASOV,KRASIMIR M, DENEVA,TEMENUZHKA D, PETKOV,LAZAR I
Year of Publication 15.02.1984

by SJAROV,STEFAN D, KIRCZEVA,RADKA S, RADENKOV,FILIP D, PETROVA,TATJANA P, ATANASOV,KRASIMIR M, PETKOV,LAZAR I
Year of Publication 15.09.1978

by RADENKOV,FILIP D, SJAROV,STEFAN D,.BG, SJAROVA,ANTOANETA D, KOMITOV,RETR G, GRIGOROV,GRIGOR R, ATANASOV,KRASIMIR M, PETKOV,LAZAR I
Year of Publication 15.06.1981