"東京都交通局,交通局について,都営地下鉄" [History of the Transportation Bureau]. kotsu.metro.tokyo.jp (in Japanese). Archived from the original on 23 February 2024. Retrieved 12 July 2024.
"会社概要" [Company Profile]. seasideline.co.jp (in Japanese). Archived from the original on 28 November 2023. Retrieved 7 February 2024.
web.archive.org
"東京都交通局,交通局について,都営地下鉄" [History of the Transportation Bureau]. kotsu.metro.tokyo.jp (in Japanese). Archived from the original on 23 February 2024. Retrieved 12 July 2024.
"会社概要" [Company profile]. akita-nairiku.com (in Japanese). Archived from the original on 30 November 2023. Retrieved 7 February 2024.
"会社概要" [Company Profile]. seasideline.co.jp (in Japanese). Archived from the original on 28 November 2023. Retrieved 7 February 2024.