1. Belnap, N.: A useful four-valued logic. In: Dunn, M. (ed.) Modern Uses of Multiple-Valued Logic, pp. 8–37. Reidel, Boston (1977)
2. Béziau, J.-Y.: A new four-valued approach to modal logic. Log. Anal. 54(213), 109–121 (2011)
3. Chiffi, D., Schang, F.: The logical burdens of proof: assertion and hypothesis. Log. Log. Philos. (2017). doi: 10.12775/LLP.2017.006
4. Dummett, M.A.E.: The Logical Basis of Metaphysics. Harvard University Press, Cambridge (1991)
5. Dummett, M.A.E.: Elements of Intuitionism. Oxford University Press, Oxford (2000)