Text ( visual ) : unmediated Learning, speech and thought in the mentally retarded : proceedings of Symposia 4 and 5 held at the Middlesex Hospital Medical School on 31 October 1969 and 20 March 1970 under the auspices of the Institute for Research into Mental Retardation, London / edited by A. D. B. Clarke and M. M. Lewis. -- London : Butterworths for the Institute for Research into Mental Retardation , 1972. -- vii, 83 p. : ill. ; 23 cm. -- Includes bibliographies. -- ISBN 0407249508 ; (BA13602305) ; https://ci.nii.ac.jp/ncid/BA13602305 Author Heading(s): Clarke, A. D. B. (Alan Douglas Benson) ; Lewis, Morris Michael ; Institute for Research into Mental and Multiple Handicap. -- Classification(s): LCC : RJ506.M4 ; DC : 371.9/28. -- Subject Heading(s): LCSH : Mentally handicapped children -- Language -- Congresses ; LCSH : Mentally handicapped children -- Education -- Congresses ; MESH : Education of mentally retarded -- Congresses ; MESH : Learning disorders -- Congresses