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The 21st Army was a German field army in World War II.
On 27 April 1945, towards the end of the war in Europe, the 21st Army was formed from Headquarters, 4th Army as part of Army Group Vistula (Heeresgruppe Weichsel) and fought until 8 May 1945.
- Tessin, Georg (1970). Die Landstreifkräfte 15–30 [Ground forces 15 to 30]. Verbände und Truppen der deutschen Wehrmacht und Waffen-SS 1939-1945 (in German). 4. Osnabrück: Biblio.
- Ziemke, Earl F. (2002). Stalingrad to Berlin: The German Defeat in the East. Washington D.C.: Center of Military History, US Army. ISBN 9781780392875.