福岡市地下鉄空港線・箱崎線へ新型車両「4000系」導入 24年秋ごろ運用開始 [New 4000 series trains to be introduced on the Fukuoka City Subway Kuko Line and Hakozaki Line. Operation will begin around fall 2024.]. Tetsudo Channel (in Japanese). 30 November 2023. Retrieved 30 November 2023.
