Childcraft :  The how and why library. 

 - [1969 ed.] 
 - Chicago :  Field Enterprises Educational Corp,  [1969]. 
 - 15 v. :  illus. (part col.). 
 - 031 .
<br/><br/> -v. 6. How things change.-  v. 15 (1978, 447 p) : 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Children's encyclopedias and dictionaries
<br/><br/><label>Dewey Class. No.: </label>031