I think the reasoning is that these guides, authorized or not, count as literary criticism or analysis.
But what constitutes Fair Use is always decided on a case by case basis, once it comes to a suit in court. The law remains murky.
Let's see if the link works now:
http://news.yahoo.com/s/ap/20080417/...ter_lawsuit_35
No. I'll try something else.
Still didn't work.