Learning Combinatorial Species. I have been reading the book conceptual mathematics(first edition) and I'm also about halfway through Diestel's Graph theory (4th edition). I was wondering if I was able to start learning about combinatorial species. This is very interesting to me because I love combinatorics and it makes direct use of category therory.
Also, what are some good resources to understand the main ideas behind the area and understand the juciest part of it? 
Regards, and thanks to Anon who told me about this area of math.

Applied Finite Group Actions by Adalbert Kerber roots most of its theory in combinatorial species, and begins with their comprehensive and intuitive introduction in the first chapter.
