Jinming Lu, Felix Hoehne, Andre R. Stegner, Lukas Dreher, Martin Stutzmann, Martin S. Brandt, Hans Huebl: High-resolution electrical detection of free induction decay and Hahn echoes in phosphorus-doped silicon. 2011Physical Review B: 83. ISBN 1098-0121 http://dx.doi.org/10.1103/PhysRevB.83.235201