Prawitz, Dag <br/><br/>
Natural Deduction: A Proof-Theoretical Study 

 - New York  Dover Publications  2006 
 - viii, 113p. 
<br/><br/><label>ISBN: </label>9780486446554 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Logic, Symbolic and mathematical
<br/><br/><label>Dewey Class. No.: </label>162  / Pra