Hiromi Ban, Hidetaka Nambo and Takashi Oyabu. Determining the Relative Difficulty of English Writings by Fuzzy Reasoning and Its Application to Selecting Teaching Materials. MPLLE-V9 [Internet]. 2021 Aug. 26 [cited 2026 Jul. 21];:1-12. Available from: https://stm.bookpi.org/MPLLE-V9/article/view/3592