Opalvh, Robert Edward <br/><br/>
The role of complexity in Piaget's object permanent tasts  [microform] / 
Robert Edward Opalch 
 - Ann Arbor, Mich. :  University Microfilms International,  1979 
 - 1 microfilm reel :  positive ;  35 mm. 
<br/><br/>Thesis (Ph.D.) - University of California, 1978 
<br/><br/><label>Subjects--Personal Names: </label><br/>Piaget, Jean, 1896