by Esipko E.A.[SU], Khadzhiev S.N.[SU], Prokof'ev V.P.[SU], Atanasov A.[BG], Agaronov V.A.[SU], Martynenko A.G.[SU], P"rvanev L.[BG], Khristov V.[BG]
Year of Publication 27.03.1996