1. Dăscălescu, S., Năstăsescu, C., Raianu, Ş.: Hopf algebras: an introduction. In: Pure and Applied Mathematics, vol. 235, Marcel Dekker, New York (2000)
2. Freyd, P.: Abelian categories. An introduction to the theory of functors. In: Harper’s Series in Modern Mathematics. Harper & Row, New York (1964)
3. Gabriel, P.: Des catégories abeliennes. Bull. Soc. Math. France 90, 323–448 (1962)
4. Goodearl, K.R.: Von Neumann Regular Rings, 2nd edn. Krieger, Melbourne, Fl (1991)
5. Lancaster, P., Tismensky, M.: The Theory of Matrices, 2nd edn, Academic Press, Orlando, FL (1985)