Hughes, G. E. <br/><br/>
A New introduction to modal logic / 
G. E. Hughes, M. J. Cresswell. 
 - London :  Routledge,  1996. 
 - x, 421 p. :  iill. ;  23 cm. 
<br/><br/>Includes bibliographical references (p. 384-397) and index. 
<br/><br/><label>ISBN: </label>0415125995  RM168.96 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Modality (Logic).