Hughes, G. E.  1918- <br/><br/>
A new introduction to modal logic / 
G.E. Hughes, M.J. Cresswell. 
 - London ;  New York :  Routledge,  1996. 
 - x, 421 p. :  ill. ;  23 cm. 
<br/><br/>Includes bibliographical references (p. 384-397) and index. 
<br/><br/><label>ISBN: </label>0415125995 0415126002  (pbk.) 
<br/><br/><label>LCCN: </label>95014728 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Modality (Logic)