Can you suggest books or any resource that will help understand DOS graph discussions in journal articles? I am reading DFT results. I try very hard to understand how their discussion is related to DOS graph presented, but I can't no matter how I reread it over and over again. Basically, these are the things I want to know initially: (1) How they identify that this certain peak is 4s, 2p, 3d, etc. (2) How they know that this 4s peak iof one atom is strongly hybridized with 3d peak of another atom. (3) What is the significance if the peak is above or below the Fermi level. (4) What is the significance if the peak shifted above or below the dirac point. (5) What is the significance of the fermi level? or the dirac point? Thank you very much.