There are many more excellent resources, most of them crosslinked in
one of the learning section.

### Important resources

* [The Common Lisp HyperSpec](http://www.lispworks.com/documentation/common-lisp.html),
  by X3J13 committee. The Common Lisp Standard
* [Common Lisp the Language, 2nd Edition](http://www.cs.cmu.edu/Groups/AI/html/cltl/cltl2.html),
  by Guy Steele
* [Common Lisp Document Repository](http://cdr.eurolisp.org/) a
  collection of emergent and de-facto standards
* [Common-Lisp.net](http://common-lisp.net/), project hosting and
  gateway
* [The Common Lisp Wiki](http://www.cliki.net/)

### Free books

There are many other great books you can find links to. These are the
most popularly linked introductory works.

* [Practical Common Lisp](http://www.gigamonkeys.com/book/), by Peter
  Seibel
* [Common Lisp: A Gentle Introduction to Symbolic Computation](http://www-cgi.cs.cmu.edu/afs/cs.cmu.edu/user/dst/www/LispBook/index.html) (PDF),
  by David S. Touretzky
* [Common Lisp: An Interactive Approach](http://www.cse.buffalo.edu/~shapiro/Commonlisp/) (PDF),
  by Stuart C. Shapiro
* [Successful Lisp: How to Understand and Use Common Lisp](http://psg.com/~dlamkins/sl/cover.html),
  by David B. Lamkins

Following these are two more advanced books, but beginners shouldn't
be afraid of them, they're quite accessible and "classics".

* [On Lisp](http://www.paulgraham.com/onlisptext.html), by Paul Graham
* [Structure and Interpretation of Computer Programs](http://mitpress.mit.edu/sicp/),
  by Abelson, Sussman, and Sussman

The last is actually on a related Lisp dialect, Scheme, but it's very
helpful book, generally. If you find you prefer Scheme, it's an
excellent start.