%0 Journal Article %A N. Bozhinov %T On the Root Function Expansion of a Nonlocal First Order Integro-Differential Operator %J Mathematica balkanica %D 1998 %P 225 %V 12 %N 1-2 %I mathdoc %U http://geodesic.mathdoc.fr/item/MABA_1998_12_1-2_a18/ %F MABA_1998_12_1-2_a18