1. J. Adámek, H. Herrlich, G. E. Strecker. Abstract and Concrete Categories, Wiley, New York, 1990.
2. H. L. Bentley. Normal nearness spaces, Quaestiones Math. 2 (1977), 23–43 and 513.
3. H. L. Bentley. Strict extensions of T 1 spaces. In: Recent Developments of General Topology and its Applications, International Conference in Memory of Felix Hausdorff (1868–1942), Berlin (1992), 33–45.
4. H. L. Bentley and H. Herrlich. Completion as reflection, Comment Math. Univ. Carolinae, 19 (1978), 541–568.
5. H. L. Bentley and H. Herrlich. Extensions of topological spaces. In: Topology, Proc. Memphis Conf., 1975, Marcel Dekker (1976), 129–184.