Sigel, Irving E. <br/><br/>
Logical thinking in children; research based on Piaget's theory / 
edited by Irving E. Sigel and Frank H. Hooper. With foreword by Barbel Inhelder. 
 - New York :  Rinehart and Winston,  1968. 
 - xv, 541 p. :  ill. ;  24 cm. 
<br/><br/>Includes bibliographies. 
<br/><br/><label>Subjects--Personal Names: </label><br/>Piaget, Jean, 1896--.
<br/><br/><label>Subjects--Topical Terms: </label><br/>Conservation of substance (Psychology).<br/>Child psychology.