Hello everyone! I am using Arducopter code 2.8.1 for my project of developing a stabilized quadrotor! Iwant to understand the code so i want if anyone can tell me about some papers or some thing from which i can get an inside of code!

I have already read DCM Draft and MagnetometerOffsetNulling methods used in Arducopter code! 

Pls refer me some thing else which can help me out!