It's not just history books, but capitalist control over media in general. Beyond selectively reporting facts, ideology is constantly reinforced. It's how workers end up acting against their own material interest so often, when acting collectively in solidarity with their fellow workers would gain them far more of their labour's value.

Remember Iraq WMDs? At the time, there was almost complete consensus on them being real and necessitating war. Now, we know it was entirely made up. The same is true of many movements and countries that oppose (for various reasons) US and EU imperialism.

If you don't have a significant sample of Eastern Europeans at hand, here's an article summarising the situation (https://thecommunists.org/2019/07/26/news/workers-eastern- europe-former-ussr-prefer-socialism/). It references many sources that I recommend you read. Many of the sources are capitalist and contain clear propaganda to that end, but also contain useful raw data.