[1] プリント - 2011sibe1.pdf, http://repository.tufs.ac.jp/bitstream/10108/95113/1/2011sibe1.pdf#page=11
[2] Proposal to add Katakana Letter Small Ne - 25042-katakana-letter-small-ne.pdf, , https://www.unicode.org/L2/L2025/25042-katakana-letter-small-ne.pdf
[3] Recommendations to UTC #183 (April 2025) on Script Proposals - 25091-sew-recommendations-utc183.pdf, , https://www.unicode.org/L2/L2025/25091-sew-recommendations-utc183.pdf#page=15
[4] 終助詞での使い分けは orthographical ではなく typographical な違いに過ぎないと強弁する Unicode。