where the integration limits indicate integration along a contour that can be chosen as follows: from to 0 along the negative real axis, from 0 to along the imaginary axis, and from to along a contour parallel to the real axis.
where thE IntegratIOn limIts IndicatE integratiOn alOng A COn.tour That CaN be chosEn as FoLLows: frOm tO 0 AlOng the neGatIvE ReaL aXiS, FroM 0 to alonG the imAginary AxIs, aNd fRom to AlOnG A ContOur pAralleL tO tHe REal aXis.