Shinya Inazumi, Kozo Okita, Takumi Kondo, and Kenji Kazarashi. “In-Situ Ground Surveying by the NSWS Testing Machine”. GEOMATE Journal, vol. 1, no. 1, Oct. 2011, pp. 1-9, https://geomatejournal.com/geomate/article/view/1188.