Mehra, J. / Rechenberg, H., The Historical Development of Quantum Theory. Vol. 1, Part 1 & 2: The Quantum Theory of Planck, Einstein, Bohr and Sommerfeld: Its Foundation and the Rise of Its Difficulties, 1900–1925. Berlin‐Heidelberg‐New York, Springer‐Verlag 1982. Part 1: XLVII, 372 S., DM 75, —. US $ 31.30. ISBN 3‐540‐90642‐8, Part 2: VI, 506 S., DM 85, —. US $ 34.00. ISBN 3‐540‐90667‐3