Index to the U.S. patent classification 

 -  U.S. Dept. of Commerce, Patent and Trademark Office: 
<br/><br/> Description based on: 1980. 
<br/><br/><label>Subjects--Corporate Names: </label><br/>United States Patent and Trademark Office  Office of Documentation Planning and Support.  Manual of classification 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Patents--Classification
<br/><br/><label>GPO Item No.: </label>0257 
<br/><br/><label>Gov. Doc. Class. No.: </label>C 21.12/2: