TY  - BOOK
AU  - Hughes,G.E.
AU  - Cresswell,M.J.
TI  - An introduction to modal logic
T2  - University paperbacks,
SN  - 041629460X
U1  - 160 
PY  - 1972///, c1968]
CY  - London
PB  - Methuen
KW  - Modality (Logic)
N1  - "Distributed in the U.S.A. by Barnes and Noble, Inc."; Bibliography: p. [356]-371
ER  -