Field equations allowing for magnetic currents and charges

Here j and are the densities of extraneous magnetic currents and magnetic charges, respectively, which arc interrelated by a continuity ccpiation similar to (8.5)  

Equations (8.56) - (8.59) become particularly elegant and symmetric when transformed to the frequency domain 

The forth equation in (8.62) can be obtained by applying the divergence operator V to both sides of the first equation and allowing for the continuity equation for the extraneous currents and charges. In particularly, the Helmholtz equations (8.31) can be written as follows 

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