An introduction to modal logic 2026-02-15T20:31:58+03:00 DEBUG: VuFind\ILS\Driver\Folio: Token taken from global cache: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiO... - Hughes, G. E. (George Edward), 1918-; Cresswell, M. J. (University paperbacks,, 1972)