Equation Icon  ( ) riArjA 1-( i j ij ) -∂2--- 1-- r6 = 8 δ kδ l + δ δkl ∂ykyl r2 , (126 ) Aj ( ) A ri1r2 -∂---∂-- -1-- r3r3 = ∂zi ∂zi r1r2 . (127 ) 1 2 1 2