ALU: Learning Lisp
the site gives listings of books, reference material, and other resources. There is a also a guide to Lisp programming style
Basic Lisp Techniques
by David J. Cooper in PDF format
Common Lisp the Language, 2nd Edition
This document contains the complete text of the book, Common Lisp the Language, 2nd edition by Guy L. Steele, Thinking Machines, Inc.
Episodic learner model - The adaptive remote tutor
this text has been written to provide a quick introduction to the basic elements of Common LISP for both experienced and novice programmers. It is not intended to be a comprehensive account of the language