@article{pfenning-2001-a, title={A judgmental reconstruction of modal logic}, volume={11}, ISSN={1469-8072}, url={http://dx.doi.org/10.1017/s0960129501003322}, DOI={10.1017/s0960129501003322}, number={4}, journal={Mathematical Structures in Computer Science}, publisher={Cambridge University Press (CUP)}, author={PFENNING, FRANK and DAVIES, ROWAN}, year={2001}, month=July, pages={511–540} }