1. Dan, T., 1883, Trans. Seism. Soc. Japan,5, p. 94–104.
2. Hiraga, S., Miyazaki, T., Minakami, T., Utsunomiya, T., 1967,Observation of volcanic tremors at Hakone Volcano and Nasu Volcano. J. Voleanolog, Soc. Japan, II,12, 89 pp.
3. Iwasaki, I., 1970, « Kazan Kagaku » (Chemical Volcanology) — Magmatic Emanation and Volcanic Emanation, p. 70–72, 143–144.
4. -----,Katsura, T., Kamada, M., 1960,Variation of radon content of fumarolic gases in Oowakidani, Hakone Volcano. J. Volcanolog. Soc. Japan, II,5, 57 pp.
5. —————, 1966,Differentiation of volcanic emanation around the boiling point of water in geothermal regions in Japan. Bull. Volcanologique,29, p. 517–528.