Rate and direction of inventive activity    economi    

 -  1962 
 - Its special conference series, B. .
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Engineering
<br/><br/><label>Dewey Class. No.: </label>D6,78obX, K2