%0 Journal Article %A L. A. Ivanov %T On lacunae for operators splitting into Euler–Poisson–Darboux factors %J Doklady Akademii Nauk %D 1977 %P 535-538 %V 233 %N 4 %U http://geodesic.mathdoc.fr/item/DAN_1977_233_4_a6/ %G ru %F DAN_1977_233_4_a6