Ross Alf <br/><br/>
Directives and norms. 

 - London  Routledge         1968 
 - ix,188p.  cm. 
 - International library of philosophy and scientific methods. .
<br/><br/><label>Standard No.: </label>43337 
<br/><br/><label>Source: </label> Textual 
<br/><br/><label>Dewey Class. No.: </label>R1, K8