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2. John Perry, Spinning Tops, 1890, S. 112; deutsch vonA. Walzel, 1913, S. 90.
3. M. Abraham, Ann. Physik10, 151, 169, 171 (1903).
4. O. M. Richardson, Physic. Rev.26, 248 (1908).
5. S. J. Barnett, Science (N. Y.)30, 413 (1909).