TY  - BOOK
AU  - Hughes, G E
TI  - An Introduction to Modal Logic
U1  - N14 
PY  - 1968///
CY  - London
PB  - Methuen & Co Ltd
N1  - includes index and biblioraphy; Non-modal propositional calculus  The lower predicate calculus  Modality and existence  Identity and description in modal lpc  The lewis system  Validity and decision procedures for various systems  Non-standard systems  Boolean algebra and modal logic
ER  -