Books on Amazon
Psychology/Content/Field: it may be that Boolean structure for a psychological theory is sufficiently - (> possible world/Field) - but then belief must be more than indication (display) - ((s) then it just comes down to the cardinality the quantities of possible worlds - then we do not need intrinsically representational content).
Realism, Mathematics and Modality Oxford New York 1989
Truth and the Absence of Fact Oxford New York 2001
Science without numbers Princeton New Jersey 1980