Kinoshita, Kenji (30 November 2023). JR九州813系、全車両をロングシート化 - 12月以降、順次運用開始へ [JR Kyushu to install long seats on all 813 series trains from December]. Mynavi News (in Japanese). Retrieved 3 January 2025.
JR九州813系ロングシート化、2024年度末までに32編成で工事完了へ [JR Kyushu to install long seats on 813 series trains, 32 trains to be completed by the end of fiscal 2024]. Mynavi News (in Japanese). 3 January 2025. Retrieved 3 January 2025.