Default values for get &c
A short article on the default values for property list accessors.
The Idiot's Guide to Common Lisp Packages
A tutorial by Ron Garret on Common Lisp packages. It covers symbols, values and the REPL loop, interning, home packages, exporting symbols and using packages, shadowing, and DEFPACKAGE.
The Idiot's Guide to Special Variables and Lexical Closures
A tutorial by Ron Garret on Common Lisp special variables. It covers variables and bindings, lexical and dynamic scope, DEFVAR, and lexical closures.