1. For an overview and references, see the many other articles in this book
2. R.P. Feynman, R.B. Leighton, M.L. Sands: The Feynman Lectures on physics, Vol. III: Quantum Mechanics ( Addison-Wesley, Reading, MA 1965 )
3. W. Heisenberg: Z. Phys. 43, 172 (1927)
4. C.J. Davisson, L.H. Germer: Nature 119, 558 (1927)
5. G. Möllenstedt, C. Jönsson: Z. Phys. 155, 472 (1959)