"55020". Railcar.co.uk. Archived from the original on 14 April 2018. Retrieved 13 April 2018.
"55020 Details". Railcar.co.uk. Archived from the original on 14 April 2018. Retrieved 13 April 2018.
"55022 Details". Railcar.co.uk. Archived from the original on 14 April 2018. Retrieved 13 April 2018.
"55025". Archived from the original on 30 October 2016. Retrieved 29 October 2016.
"55026". Railcar.co.uk. Archived from the original on 14 May 2021. Retrieved 13 April 2018.
"55034". Archived from the original on 7 July 2018. Retrieved 20 January 2021.
"Hornby BR Class 121". Hornby Railways Collector Guide. Archived from the original on 11 January 2020. Retrieved 2 February 2020.
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Fox 1987, pp. 30–31 Fox, Peter (1987). Multiple Unit Pocket Book. British Railways Pocket Book No.2 (Summer/Autumn 1987 ed.). Platform 5 Publishing Ltd. ISBN0906579740. OCLC613347580.
Leigh, Chris (Autumn 1998). "Lima Class 121 diesel railcar". Model Rail. No. 4. Peterborough: EMAP Apex. pp. 86–87. ISSN1369-5118. OCLC173324502.
Wild, Mike (April–May 2007). "BR blue and BR green for the Class 121 railcar". Hornby Magazine. No. 1. Hersham: Ian Allan Publishing. p. 80. ISSN1753-2469. OCLC226087101.