1. J. Adámek, H. Herrlich, G. E. Strecker, Abstract and concrete categories, New York: Wiley, 1990.
2. M. Baran, Separation properties, Indian J. Pure Appl. Math., 23 (1991), 333–341.
3. M. Baran, Generalized local separation properties, Indian J. Pure Appl. Math., 25 (1994), 615–620.
4. M. Baran, H. Altındis, $T_{0}$-objects in topological categories, J. Univ. Kuwait (Sci.), 22 (1995), 123–127.
5. M. Baran, Separation properties in topological categories, Math. Balkanica, 10 (1996), 39–48.