An internet search reveals quite a few articles written by those who've done deeper studies on this subject. Here are a couple:
http://www.bereanpublishers.com/trouble-in-narnia-the-occult-side-of-c-s-lewis/
http://spaceforswashbuckling.blogspot.com/search/label/Narnia
RE: Sci-Fi and Fantasy Is Steeped in Luciferian Propaganda