Observation of a long-lived multiple optical echo Akhmediev, N. N. ; Borisov, B. S. ; Zuǐkov, V. A. ; Samartsev, V. V. ; Stel'Makh, M. F. ; Usmanov, R. G. ; Fomichev, A. A. ; Yakshin, M. A. Abstract Publication: ZhETF Pisma Redaktsiiu Pub Date: December 1988 Bibcode: 1988ZhPmR..48..585A