Besides this first report (AIM-001), some of the reports following it in the next months are at least as important, by introducing other essential features of LISP and of many later languages:

1958-10: AIM-003 (the special form "maplist", i.e. a kind of "forall" iteration)

1958-10: AIM-004 (anonymous function definitions using "lambda"; the special form "select", which already at that early date had better syntax and semantics than the "switch" or "case" statements of later languages; the special form "search")

1959-03-13: AIM-008 (the special form "quote"; the special form "label", for defining anonymous recursive functions; also the special forms "and" and "or", a.k.a. McCarthy AND and McCarthy OR, inherited by many languages, including C)