Code С++ shaders for cycles

Hi. From now i can build blender from source.
So how can i start to create new closures for cycles. Please show me the way. I am interested in it.
For example I recreate Fresnel node with Schlick’s approximation using blender nodes. Now I want to learn how to do it with c++.
My goal is to learn how to write custom shaders. No OSL please. Mb some articles or tutors???

Nope, I dont think there are any, did you try to follow the code and see how it works? - you could also check git history for commits which added new shaders, this gives you a list of required changes.

This is exactly what I am doing for some weeks =)