"Narnia" explantions

I am looking for a really good book explaining all things Narnian -- the literary and historical allusions, references, sources for names/places, etc.... It doesn't need to be too technical/professorial since I'll mainly be discussing the book with 8 -12 year olds, but I don't want a simple children's book either. I have Companion to Narnia by Paul Ford, which isn't bad, but any other suggestions would be appreciated... any ideas?

I am also interested in one for Lewis Carroll/Wonderland...

Thank you very much for your consideration...

sorry, didn't realize nobody lived here anymore...

The volumes (2 so far) by Devin Brown are good literary commentaries. The recent Planet Narnia by Michael Ward has had some great reviews and offers some unique analysis. I haven't read that yet, so I'm not sure how academic it is. Other good authors with work on Narnia in general: Bruce Edwards, Peter J Schakel, and David C. Downing

Another book to consider is The C. S. Lewis Encyclopedia by Colin Duriez. It isn't Narnia specific, but mentions with some detail some of the main topics and characters in Narnia. Duriez takes a little more subjective liberties in interpreting their meanings in his encyclopedia.

Also, Narnia can never be fully understood until one is acquainted with the author. Studying Lewis will add new dimension to the Narnia series.

I don't think Planet Narnia will hellp ypu much with your 8-12 year olds, but it is an excellent book for any Narnia-lover to read.
Lewis' Letters to Children could be a good resource for you.