Prawitz, Dag <br/><br/>
Natural deduction :  A proof theoretical study / 
by Dag Prawitz 
 - New  York :  Dover Publications ,  1965 . 
 - 113 p.  Paper Back 
<br/><br/><label>ISBN: </label>9780486446554 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Deduction<br/>Symbolic and mathematical <br/>Modality <br/>Logic
<br/><br/><label>Dewey Class. No.: </label>510  / DAG-N