Hart, H.L.A <br/><br/>
The concept of law 

 - 3rd ed. 
 - Oxford, UK :  Oxford University Press,  2012. 
 - lv, 325 p. ; 
<br/><br/><label>ISBN: </label>9780198934837 
<br/><br/><label>Dewey Class. No.: </label>340 HAR