- Abelian categories
- Aditive functors
- Localization
- Sheaves of sets on a topological space
- Elementary toposes
- Boolean toposes
Bibliography
- M. Barry: Theory of categories, Academic Press, 1965.
- Busneag: Categories of algebraic logic, Ed. Academiei, Bucuresti, 2006.
- P.J. Cameron: Sets, Logic, and Categories, Springer Undergraduate Mathematics Series , 1999.
- S.M. Lane: Categories for the Working Mathematician, Springer, 1997.
- C. Nastasescu: Inele. Module. Categorii, Ed. Academiei, Bucuresti, 1976.
- N.Popescu , Categorii abeliene, Ed. Academiei Romane, Bucuresti, 1971.
- N. Popescu, L. Popescu: Theory of categories, Ed. Academiei, Bucuresti si Sijthoff and Noordhoff International Publishers, 1979.
- A.Radu, Teoria toposurilor, Ed. Academiei Romane, Bucuresti, 1981.
- Gh. Radu : Algebra categoriilor si a functorilor, Ed. Junimea, Iasi, 1988.