Looking for well written Common Lisp code

I'm looking for clean, well written Common Lisp code for the purpose of studying it. I started learning Common Lisp recently and feel that looking at how other people do things would be greatly beneficial but I don't want to acquire bad habits by learning from crap which is why I'm asking.

Any suggestions?

Damn, I should proofread my posts.
It should be "If you want to see some real in-use code, read some implementation's ..."