Mental subnormality :  modern trends in research / 
edited by B. W. Richards ; with a foreword by L. S. Penrose 
 - London :  Pitman Medical,  1970 
 - x, 260 p. :  ill. ;  23 cm. 
<br/><br/>Includes bibliographies. 
<br/><br/><label>LCCN: </label>79-500621 //r863 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mental retardation--Research