Is there any best book or site(instead of docs) for unreal engine core system in c++ source code level?

Is there any best book or site (instead of docs ,wiki…) for unreal engine core system in c++ source code level?
I want something like overall unreal engine code architecture (not for gameplay, just for game engine programming like scripting system, compile system, renderer, resource management, cashing , etc.).

I already have knowledge of (c++, graphics code [opengl,directx,shader code] and basic of game engine architecture ,game & graphics programming etc…)