1. [1] Adámek, J., Herrlich, H. and Strecker, G. E., Abstract and Concrete Categories, Wiley, New York, 1990.
2. [2] Baran, M., Separation properties. Indian J. Pure Appl. Math. 23 (1992), 333-341.
3. [3] Baran, M., Stacks and filters. Turkish J. of Math.-Do˘ga. 16 (1992), 95-108.
4. [4] Baran, M., The notion of closedness in topological categories. Comment. Math. Univ. Carolinae. 34 (1993), 383-395.
5. [5] Baran, M., Generalized Local Separation Properties. Indian J. Pure Appl. Math. 25 (1994), 615-620.