1. Abstract and Concrete Categories;Adámek,1990
2. Measurement of membership functions: theoretical and empirical work;Bilgiç,2000
3. An Investigation into The Laws of Thought;Boole,1854
4. N. Bourbaki, Elements of Mathematics, General Topology, Part 1, Addison-Wesley, Reading, MA (A translation of Éléments de Mathématique, Topologie Générale, Hermann, Paris, 1966).
5. N. Bourbaki, Elements of Mathematics, Theory of Sets, Hermann, Addison-Wesley, Reading, MA (A translation of Éléments de Mathématique, Théorie des Ensembles, Hermann, Paris, 1968).