Okamoto, T. (1998) “Fossil Periglacial Phenomena on Karst in the late Quaternary in the Akka Karst, Northeastern Japan”, Geografia Fisica e Dinamica Quaternaria, 3(4), pp. 61–67. Available at: https://www.gfdq.glaciologia.it/index.php/GFDQ/article/view/1196 (Accessed: 30 July 2026).