Library congress classification:   Class a. general works polygraphy 
/Library of congress 
 - 3rd ed. 
 - Washington:   The library of congress,  1947 
 - 54p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Classification
<br/><br/><label>Subjects--Index Terms: </label>Library of congress 
<br/><br/><label>Universal Decimal Class. No.: </label>D 025.49LC