00276nam a2200097Ia 4500008004100000082001800041100002100059245005900080264002900139300001000168200527s9999||||xx |||||||||||||| ||und||  a616.858 8 ELL  aEllis, Norman R. 0aInternational Review of Research in Mental Retardation  bAcademic Press Incc1966  a366p.