I have seen several references to finding an old gramophone and only a single working record that was played incessantly during lulls in the fighting. I read that the tune was unknown to the soldiers at the time, but has there been any effort to determine the name of the tune? I first came across the information while watching the "Soviet Storm" series on youtube.
From the source that I got, it was apparently tango music, interrupted by brief communist propaganda messages. Strange yes, but tango was in fact a popular art form during '30s and '40s Soviet Russia. The book I saw it in was "Stalingrad - The Fateful Siege 1942-1943". You can find numerous clips on YouTube of old-school 1930s tango from Eastern Europe on YouTube.