TY  - BOOK
AU  - Chellas,Brian F.
TI  - Modal logic: an introduction 
SN  - 0521224764
PY  - 1980///]
CY  - Cambridge [Eng.], New York
PB  - Cambridge University Press
KW  - Modality (Logic)
N1  - Includes indexes; Bibliography: p. [278]-279
ER  -