New book of knowledge. 

 - [S.l.] :  Grolier,  [19--]. 
 - v. :  ill., maps. 
<br/><br/> Entries are written on a range of reading levels and are the work of qualified specialists.  Every volume is separately indexed. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Encyclopedias and dictionaries.
<br/><br/><label>Dewey Class. No.: </label>031