1. Adámek, J., Herrlich, H., Strecker, G.E.: Abstract and Concrete Categories, the Joy of Cats. http://katmat.math.uni-bremen.de/acc
2. Aull, C.E., Thron, W.J.: Separation axioms between $$T_0$$ T 0 and $$T_1$$ T 1 . Indag. Math. 24, 26–37 (1963)
3. Banaschewski, B., Bruns, G.: Injective hulls in the category of distributive lattices. J. Reine Angew. Math. 232, 102–109 (1968)
4. Banaschewski, B., Hager, A.: Essential completeness of archimedean $$\ell $$ ℓ -groups with weak order unit. J. Pure Appl. Algebra 217, 915–926 (2013)
5. Banaschewski, B., Hager, A.: Essential completeness in categories of completely regular frames. Appl. Categ. Structures 21, 167–180 (2013)