I would suggest On Contradictions as a starter for Mao. It's a little dense and might take a few readings to fully grasp (did for me at least) but it informs you of the outlook Mao uses for the world and his writings.

Imagine my frustration! Give me a second.

Zizek has a good book on Maoism. Julia Lovell has a great book that finally just now covers international Maoism. Maoism: A Global History.

Violence means a lot of things.