Quantum Point Contacts and Coherent Electron Focusing
  I. Introduction   II. Electrons at the Fermi level   III. Conductance quantization of a quantum point contact   IV. Optical analogue of the conductance quantization   V. Classical electron focusing   VI. Electron focusing as a transmission problem   VII. Coherent electron focusing (Experiment, Skipping orbits and magnetic edge states, Mode-interference and coherent electron focusing)   VIII. Other mode-interference phenomena 
H. van Houten, C. W. J. Beenakker