"青函トンネル:新幹線対応 電圧アップ2万5000Vに" [Seikan Tunnel voltage raised to 25000 volts for Shinkansen compatibility]. Mainichi Shimbun (in Japanese). The Mainichi Newspapers. 2016-03-22. Archived from the original on 2016-03-22. Retrieved 2016-04-03.
"青函トンネル:新幹線対応 電圧アップ2万5000Vに" [Seikan Tunnel voltage raised to 25000 volts for Shinkansen compatibility]. Mainichi Shimbun (in Japanese). The Mainichi Newspapers. 2016-03-22. Archived from the original on 2016-03-22. Retrieved 2016-04-03.