TY  - BOOK
AU  - Hughes G E
AU  - Cresswell M J
TI  - New introduction to modal logic
SN  - 978-0-415-12600-7
U1  - 511.314 
PY  - 2001///
CY  - London
PB  - Routledge
KW  - Modal logic
KW  - Modality (Logic)
ER  -