%0 Journal Article %A N. Bozhinov %A E. M. Elabd %T Joint Root Function Expansion of the Nonlocal Partial Integro-Differential Operators of First and Second Order %J Mathematica balkanica %D 1998 %P 253 %V 12 %N 3-4 %I mathdoc %U http://geodesic.mathdoc.fr/item/MABA_1998_12_3-4_a0/ %F MABA_1998_12_3-4_a0