1. J. Adáimek, H. Herrlich, G. Strecker, Abstract and Concrete Categories (Wiley, New York, 1990).
http://katmat.math.uni-bremen.de/acc/acc.pdf
2. G. Birkhoff, Lattice Theory. American Mathematical Society, vol. 25, 2nd ed. (Colloquium Publications, New York, 1948)
3. C.B. Boyer, The History of the Calculus and its Conceptual Development (Dover Publications, New York, 1959)
4. Coalgebra.
https://en.wikipedia.org/wiki/Coalgebra
5. H. Ehrig, M. Pfender, Kategorien und Automaten (Walter de Gruyter, Berlin, 1972)