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2. L. V. Bewley: Traveling Waves on Transmission Systems (Dover, New York 1951) p. 210
3. G. A. Campbell: Bell Syst. Tech. J. 2, 1–30 (1923)
4. O. Mayr: ETZ 36, 1352–1355
5. O. Mayr: ETZ 38, 1436–1440 (1925)