"E331系AK1編成長野へ配給" [E331 series set AK1 moved to Nagano]. RM News (in Japanese). Japan: Neko Publishing Co., Ltd. 27 March 2014. Archived from the original on 27 March 2014. Retrieved 10 April 2014.
jrchiba.jp
E331系の運転再開について [Return of E331 series to service] (PDF). News release (in Japanese). Chiba, Japan: East Japan Railway Company – Chiba Branch. 19 December 2008. Archived from the original(PDF) on 19 February 2012. Retrieved 11 October 2011.
railf.jp
"E331系ケヨAK1編成が営業運転に" [E331 series set AK1 in revenue service]. Japan Railfan Magazine Online (in Japanese). Japan: Koyusha Co., Ltd. 5 April 2010. Retrieved 11 October 2011.
web.archive.org
E331系の運転再開について [Return of E331 series to service] (PDF). News release (in Japanese). Chiba, Japan: East Japan Railway Company – Chiba Branch. 19 December 2008. Archived from the original(PDF) on 19 February 2012. Retrieved 11 October 2011.
"E331系AK1編成長野へ配給" [E331 series set AK1 moved to Nagano]. RM News (in Japanese). Japan: Neko Publishing Co., Ltd. 27 March 2014. Archived from the original on 27 March 2014. Retrieved 10 April 2014.