Principles of War for the Information Age
I consider this one essential for really understanding the enduring and unchanging nature of war.

For CvC I consider this about the best analysis I have read so far.

Another Bloody Century by Colin Gray is an excellent antidote to the US "new war" fad, and War, Peace, and International Relations: An Introduction to Strategic History is an excellent primer to understanding what strategy actually is.

Strategy for Chaos is also very good.