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[21] An. d. Phys., 43, 96, 1914.
[22] Phys. Zeit., 18, 121, 1917.
[23] Phys. Zeit., 21, 322, 1922.
[24] Proc. Copenhagen Ac., 1919.
[25] Physica, 4, 337, 1924.
[26] Physica, 4, 340, 1924.
[27] Zeit. f. Tech. Phys., 5, 2, 1925.
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