Chellas, Brian F. <br/><br/>
Modal logic :  an introduction / 
Brian F. Chellas 
 - Cambridge :  The University Press,  c1980 
 - xii, 295 p. :  ill. ;  23 cm. 
<br/><br/>Includes bibliographical references and index 
<br/><br/><label>ISBN: </label>0521295157 :  PND 17.50 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Modality (Logic)
<br/><br/><label>Dewey Class. No.: </label>160