FLÓREZ, Jorge Alejandro. Topology of Modal Propositions Depicted by Peirce’s Gamma Graphs: Line, Square, Cube, and Four-Dimensional Polyhedron. Logic and Logical Philosophy. Online. 30 November 2021. Vol. 31, no. 3, pp. 457-470. [Accessed 17 August 2024]. DOI 10.12775/LLP.2021.017.