A question for faculty out in VIPEr land, most likely of the solid state variety:

Does anyone teach bond valence sums or bond valence analysis in their inorganic courses?  I have not taught this topic in the past, but I have students reading a paper for class this semester that discusses bond valence analysis and bond valence parameters briefly.  I am looking for some leading references to point them to (juniors and seniors) that would gently introduce them to this topic.  Any suggestions either online or in texts or in the literature?