JESS: good book on Fuzzy Logic & RBS ?

[David]

Hello all,   I recently purchase the Jess in Action book. It is an excellent hands on book with lots of examples and teaches one how to code RBS stuff and also FuzzyJ toolkit (HVAC topic).   However, I am extremely new to Fuzzy and RBS. I wonder if anyone has any recommendations for any book that may be a good companion to the Jess In Action to provide some elementary /fundamental concepts of Rule Based System (RBS) or Fuzzy Logic with RBS.   Many thanks for your time and attention.     Regards David