Library of Congress  Subject Cataloging Division <br/><br/>
Classification :  Class Q : Science. 

 - 5th ed. (with supplementary pages) 
 - Washington :  Govt. print. off,  1950 (reprinted 1954). 
 - 216, 15 p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Classification--Books--Science<br/>Classification, Library of Congress<br/>Classification--Books--General works