1. Aull, C. E. Classification of topological spaces. Bull. Acad. Polon. Sci. Sér. Sci. Math. Astronom. Phys. 15 (1967), 773–778.
2. Gardner, B. J., and Jackson, M. The Kuratowski closure-complement theorem. New Zealand J. Math. 38 (2008), 9–44.
3. Gillman, L., and Jerison, M. Rings of continuous functions. The University Series in Higher Mathematics. D. Van Nostrand Co., Inc., Princeton, N.J.-Toronto-London-New York, 1960.
4. Herda, H.-H., and Metzler, R. C. Closure and interior in finite topological spaces. Colloq. Math. 15 (1966), 211–216.
5. Kuratowski, C. Sur l’opération a de l’analysis situs. Fundamenta Mathematicae 3, 1 (1922), 182–199.