Manual of Classification. 

 - Washington, D.C.  U.S. Dept. of Commerce, Patent and Trademark Office, Search znd Information Resources  For sale by the Supt. of Docs., G.P.O 
<br/><br/> Description based on: Dec.1992, basic manual. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Patents--Classofication--United States--Periodicals.
<br/><br/><label>GPO Item No.: </label>0258 
<br/><br/><label>Gov. Doc. Class. No.: </label>C 21.12: