1. Lava flows in the southern part of Aso caldera;Baba M;Journal of the Kumamoto Geoscience Association,1999
2. Fundamental studies of plant opal analysis 1: on the silica bodies of motor cell of rice plants and their near relatives, and the method of quantitative analysis;Fujiwara H;Archaeology and Natural Science (Biannual Journal of the Japanese Society for Scientific Studies on Cultural Property),1976
3. Fundamental studies in plant opal analysis 2: the shape of the silica bodies of Oryza;Fujiwara H;Archaeology and Natural Science (Biannual Journal of the Japanese Society for Scientific Studies on Cultural Property),1978
4. Geospatial Information Authority of Japan.1994Land Condition Map of Aso Volcano (1 : 30 000 Scale). Geospatial Information Authority of Japan (in Japanese).
5. Vegetation changes after the late period of the Last Glacial Age based on pollen analysis of the northern area of Aso Caldera in central Kyushu, Southwest Japan