T. Okamoto, “Fossil Periglacial Phenomena on Karst in the late Quaternary in the Akka Karst, Northeastern Japan”, Geog. Fis. Dinam. Quat., vol. 3, no. 4, pp. 61–67, Jan. 1998, Accessed: Apr. 29, 2026. [Online]. Available: https://www.gfdq.glaciologia.it/index.php/GFDQ/article/view/1196