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**Ackbeet** Try Blatt and Weisskopf's *Theoretical Nuclear Physics,* Appendix B, and Morse and Feshbach's *Methods of Theoretical Physics,* Section 13.3. Those are references I found in Jackson's Classical Electrodynamics, 3rd. Ed., p. 449. Jackson uses vector spherical harmonics, but it doesn't look like he gives an exposition of their theory (proof of completeness, for example, which physicists are notoriously bad at providing - either that, or they just try to show they can get the Dirac Delta function from some linear combination of the functions).

Cheers.