TY  - BOOK
ED  - United States Patent and Trademark Office (USPTO) <Washington>
TI  - Development and use of patent-classification-systems
PY  - 1966///
CY  - washington: 
PB  - U.S. Gov.Print.Off., 
KW  - Patentklassen
KW  - USA
N1  - 14.047, 14.048
ER  -