This is another good one: http://www.cambridge.org/gb/academic/subjects/mathematics/logic-categories-and-sets/conceptual-mathematics-first-introduction-categor

This is another good one: http://www.cambridge.org/gb/academic/subjects/mathematics/logic-categories-and-sets/conceptual-mathematics-first-introduction-categories-2nd-edition http://www.cambridge.org/gb/academic/subjects/mathematics/lo...