[1](http://en.wikipedia.org/wiki/Outline_of_category_theory)
[2](http://lambda1.jimpryor.net/advanced_topics/monads_in_category_theory/)
[3](http://en.wikibooks.org/wiki/Haskell/Category_theory)
-[4](https://wiki.haskell.org/Category_theory), where you should follow the further links discussing Functors, Natural Transformations, and Monads.
+[4](https://wiki.haskell.org/Category_theory) <small>(where you should follow the further links discussing Functors, Natural Transformations, and Monads)</small>
[5](http://www.stephendiehl.com/posts/monads.html)