Best Book/Tutorial Available In Market/Internet Resp. For GDB.

To be precise, I am learning programming of AVRs since last 3-4 days (exciting it is), I want to learn to use GDB for tracing my AVR programs which are popping beautiful errors.

I always have trouble to learn using official documentations, If anyone knows book available in market about GDB or free tuts in internet, kindly link me. Thank you.