Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Huibin Jia,"Improvement of an Extremely Hard Soil, Pianosol",環境科学研究所報告 = Journal of Environmental Science Laboratory,13464736,美唄 : 専修大学北海道短期大学,2002,,9,55-144,https://cir.nii.ac.jp/crid/1520572358402529024,