Yep, dumping coal to lake and cover them. My father said it like manthra every time, when some about Russia or Stalin is said.

Is it true that Stalin built wide tracks in Poland to transport coal from Silesia to cover the lakes. This is something my father tells me like a mantra, and that his father and the Silesians who lived under Stalin told him about it (father born in 1956, so he did not witness it).

50 million or 70 million loses during the Second World War. Why are there such big differences?

One thing that caught my attention is how big the distribution is between the losses during the Second World War. Sometimes, whether it's in documentaries or history books, I see 50 million, and in other cases, I see numbers as high as 70 million. 20 million is a lot, where do these big differences come from? Are 50 million those who died in Europe, and 70 million leave when the Asian front is counted, or something else entirely?