You might also look into two books by P. Adams Sitney (though only the first
deals with American cinema exclusively, I think):
_Visionary film: the American avant-garde, 1943-1978_ (Oxford Univ. Press,
  ISBN 0-19-502486-9)
(as editor) _The avant-garde film: a reader of theory & criticism_ (Anthology
  Film Archives, ISBN 0-911689-08-7)
Hope this helps!
Jeff Clark
James Madison University
bitnet: fac_jclark@jmuvax1
internet: [log in to unmask]