@misc {IOPORT.03801511,
    author       = {Font, Josep M.},
    title        = {On the definition of necessity and possibility in non-classical modal logic.},
    howpublished = {Mathematical logic, Proc. 1st Catalonian Congr., Barcelona 1982, 85-88 (1982).},
    year         = {1982},
    identifier   = {03801511},
}