Editors. "Russians retake East Prussia". The Literary Encyclopedia. First published 30 December 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=17719, accessed 18 May 2013.]
Russian forces retake the territory of East Prussia. This area has been left defenceless, as the Prussian army is required elsewhere for winter campaigning in the Seven Years' War.