by Mkrtchyan, A.R, Aslanyan, H.A, Mkrtchian, A.H, Gasparian, R.H, Mkhitarian, A.Kh, Garibian, G.M, Avakian, R.H, Taroyan, S.P, Avetisyan, A.E, Kisogyan, H.S, Dallakyan, K.R, Gyurdzhyan, V.A, Danagulyan, S.S, Elbakyan, G.M, Boyakhchyan, Ye.M
Published in Solid state communications (01.07.1991)