1. Born, M. (1963). Ausgewählte Abhandlungen (Vol. 2, pp. 584–598). Göttingen: Vandenhoek and Ruprecht.
2. Burgess, A. G., & Burgess, J. P. (2011). Truth. Princeton: Princeton University.
3. Butterfield, J. (2000). Topos Theory as a framework for Partial Truth.
4. Cartan, H., Henri, & Eilenberg, S. (1956). Samuel Homological algebra. Princeton N: Princeton University Press.
5. Connes, A. (2019). Un Topo sur les Topos, personal communication. Mars, 23.