Takashi Obara, Kitao Yamamoto, Tamaki Ura, Hisaaki Maeda, Hiroyuki Yamato; Basic design of an unmanned untethered submersible with a closed cycle diesel engine, Proceedings of the Eighth International Symposium on Unmanned Untethered Submersible Technology, vol. 8, pp. 411 - 419, September 1993.