1. Bird, R., de Moor, O.: Algebra of Programming. University of Oxford, Prentice Hall Europe (1997). ISBN: 0-13-507245-X
2. Dieudonne, J: Mathematics—The Music of Reason. Springer, Berlin (1998). ISBN: 9783540533467
3. Wiki, H.: Monad. https://wiki.haskell.org/Monad
4. Wikipedia: Samuel Eilenberg. https://en.wikipedia.org/wiki/Samuel_Eilenberg
5. Wikipedia: Saunders Mac Lane. https://en.wikipedia.org/wiki/Saunders_Mac_Lane