1. R.P. Feynman, R.B. Leighton, M. Sands, The Feynman Lectures on Physics, vol. 3—Quantum Mechanics, (Addison-Wesley, Reading, 1965)
2. R.P. Feynman, R.B. Leighton, M. Sands, The Feynman Lectures on Physics, vol. 3,—Chapter 19: “The Hydrogen Atom and the Periodic Table” (Addison–Wesley, Reading, 1965)
3. J. M. Ziman, Principles of the Theory of Solids, Chapter 3—“Electron States”, (Cambridge University Press, Cambridge, 1964), pp. 72–74
4. S. M. Sze, Physics of Semiconductor Devices, (Wiley-Interscience, New York, 1969)
5. C. Kittel, Introduction to Solid State Physics, (Wiley, New York, 1967)