「大阪メトロ」新型車両400系、6/25運行開始へ - ダイヤは公開せず ["Osaka Metro" delays new 400 series introduction to 25 June]. Mynavi News (in Japanese). April 25, 2023. Retrieved April 25, 2023.
デビュー秒読み 異形の地下鉄「400系」新機軸だらけの秘密とは? 大阪メトロが動画公開 [Osaka Metro announces debut countdown for innovative "400 series" – what makes it so unusual?]. Traffic News (in Japanese). Japan: Mediavague Co., Ltd. April 14, 2023. Retrieved April 14, 2023.