1. Communication Department (1915) The 7th directory of the electric supply industry (in Japanese)
2. Communication Department (1937) List of permitted locations for hydroelectric power plants (in Japanese)
3. Communication Department (1939) The 30th directory of the electric supply industry (in Japanese)
4. Hanai S (2000) Accumulation of Capital of Light Industry. In: Ishi K, Hara A, Takeda H (eds) Economic history in Japan, vol 2. Industrial Revolution Period. University of Tokyo Press, Tokyo. (in Japanese)
5. Kamibayashi T (1948) Growth of Industry in Japan. Gakuseisyobou, Tokyo. (in Japanese)