Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) 齋藤 誠慈 and 石井 博昭 and 葉 光毅,On optimal paths in free spaces including obstacles with fuzzy boundaries of fuzzy normed spaces,神戸学院経済学論集 = Kobe Gakuin economic papers,03862038,神戸 : 神戸学院大学経済学会,2007-09,39,1・2,41-49,https://cir.nii.ac.jp/crid/1520853833001864704,