Hi PhysicsForums, I'm writing a term paper on the properties of the von Neumann Entropy, its relation to the Shannon Entropy, and the additional complications present in the von Neumann Entropy that are not present in the Shannon Entropy. Could someone direct me to articles and books that will be helpful? Thanks! My professor already directed me towards this article, which has been very helpful: A. Wehrl, "General properties of entropy," Rev. Mod. Phys. 50 (1978) 221.