00469nam a2200133Ia 4500008004100000082001800041100002400059245005400083264005200137300001000189942000500199999001700204952011400221200526s9999||||xx |||||||||||||| ||und||  a616.855 4 PER  aPerkins, William H. 0aWhite House Conference on Mental Retardation 1963  bU.S. Department of Health Education and Welfare  a153p.  c  c10904d10904  00102ddc4070876/4aAIISHbAIISHd2020-05-26l0o616.855 4 PERp2662r2020-05-26 00:00:00w2020-05-26ySTS