+ articles + misc refs to check
Steele and Sussman - The Art of the Interpreter MIT AI May 78 (->or, the modularity complex) - building an interpreter in a lisp dialect - relates to extending stuff. also interesting for modularity, environments and scope.
Structure and Interpretation of Computer Programs (online)
Nigel Morgan - symbolic composer environment
Hofstadter & Mitchell:
Scott Bolland of the University of Queensland wrote a Java version of Copycat and a tutorial
23/08 wait info from ppl initiated Magnificat - uses lexicon (replacing copycats slipnet) to give concept lexeme nodes as a top down organizing force on structureless linking in copycat model