Ueshin, Daisuke (19 July 2018). 東武鉄道20400型を公開、日光線・宇都宮線で9月デビュー! 写真83枚 [Tobu Railway 20400 series released, September debut on Nikko Line · Utsunomiya Line! 83 photos]. news.mynavi.jp (in Japanese). Mynavi Corporation. Archived from the original on 10 February 2019. Retrieved 10 February 2019.
railf.jp
Saito, Takahisa (4 September 2018). 東武20400形が営業運転を開始 [Tobu 20400 series starts commercial operation]. Japan Railfan Magazine Online (in Japanese). Japan: Koyusha Co., Ltd. Archived from the original on 10 February 2019. Retrieved 10 February 2019.
"東武鉄道20000系が渡瀬へ" [Tobu Railway 20000 series to Watase]. Japan Railfan Magazine Online. Koyusha Co., Ltd. 29 July 2017. Archived from the original on 10 February 2019.
Ueshin, Daisuke (19 July 2018). 東武鉄道20400型を公開、日光線・宇都宮線で9月デビュー! 写真83枚 [Tobu Railway 20400 series released, September debut on Nikko Line · Utsunomiya Line! 83 photos]. news.mynavi.jp (in Japanese). Mynavi Corporation. Archived from the original on 10 February 2019. Retrieved 10 February 2019.
Saito, Takahisa (4 September 2018). 東武20400形が営業運転を開始 [Tobu 20400 series starts commercial operation]. Japan Railfan Magazine Online (in Japanese). Japan: Koyusha Co., Ltd. Archived from the original on 10 February 2019. Retrieved 10 February 2019.
"東武鉄道20000系が渡瀬へ" [Tobu Railway 20000 series to Watase]. Japan Railfan Magazine Online. Koyusha Co., Ltd. 29 July 2017. Archived from the original on 10 February 2019.