1. [1] V. I. Smirnov, A Course of Higher Mathematics, Vol. 3, Part 2, 6th ed., National Publisher for Technical-Theoretical Literatures, Moscow (1958), (in Russian).
2. 日本語訳、スミルノフ、高等数学教程、第3巻、第2部、共立、東京 (1959),
3. and English translation, Pergamon, Oxford (1964).
4. [2] E. T. Whittaker, G. N. Watson, A Course of Modern Analysis, 4th ed., Cambridge University Press, Cambridge (1927).
5. [3] R. Courant, D. Hilbert, Methods of Mathematical Physics, Vol. 1, Wiley, New York (1955).