%0 Journal Article %A A. L. Litvin %A I. D. Tsvankin %T Nonstationary wave fields of point sources and %J Doklady Akademii Nauk %D 1987 %P 54-58 %V 294 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/DAN_1987_294_1_a13/ %G ru %F DAN_1987_294_1_a13