Analyzing the work of V.O. Pechatnov and I.E. Magadeev “Correspondence between I.V. Stalin, F. Roosevelt and W. Churchill during the Second World War”, A.M. Filitov comes to the conclusion that the authors anew study this classical source. Firstly, the authors traced the process of creating messages to the leaders of the “Big Three”, which was different in Moscow, Washington and London. Secondly, historians were able to show how these documents were perceived their addressees; Thirdly, the researchers placed the correspondence of the heads of the leading states of anti-Hitler coalition in the broader context of the Union's diplomacy of the war years.