1. Acta Arithmetica, 1, 83–86 (1935).
2. See Landau, Göttinger Nachrichten, 1918, 285–295. The same argument allows one to deduce the first form of Siegel’s theorem from the second.
3. Math. Zeitschrift, 37, 405–415 (1933).
4. J. London Math. Soc., 9, 289–298 (1934).
5. Quarterly J. of Math., 5, 150–160 (1934).