I remember when I was child (probably about 40 years ago), I read some story in a Russian book (I think original was Russian, not translated).
Story is the following: a man read some documentary book about WW2, but it isn't the same WW2, which we know, other events, other names, other Nazi leader (not Hitler).
And he think that if he could go to this time and kill this leader, we can save lot of lives. Then he fell asleep and transferred to this time. He managed to meet this leader and kill him.
Then we woke up at home, take this book and see that events changed, WW2 now is the same as we know and the Nazi leader was Hitler.
I'd like to find this story, so it's probably around 70th and in Russian language.
UPDATE: What else I remember: it was in a book, containing science fiction stories by different authors (for example I remember another story, where a man could use electricity instead of food and became very strong). This story (which I'm looking for) is short (2-3 pages).
To kill the Nazi leader (before they took power) the man came to one meeting and after the meeting asked the leader for a private conversation and strangled him.
Other detail: when he was in an old German (or maybe Austrian) city, he hired some man with a mustache to help with his luggage and by mistake gave him a very big banknote (because was not familiar with local currency). This mustache man took the money and disappeared very fast.
When the protagonist returned to his time, he recalled his face and understood who he was. Last sentence in this story: "What was his name? Schicklgruber? Hitler!".