Is this the book? https://books.google.com/books/about/Elementary_mathematics....

Your link points to some math review book by the same author.

I believe the author meant the drillbook such as https://issuu.com/normagee/docs/scanavi_sbornik_konkursnih_z....

The USSR made some amazing contributions to technology, but it's a bit of an exaggeration to say that it "gave birth to human travel in space" which to me implies that it was a novel technology nobody else was working on and wouldn't have happened any time soon without them.

The first manned US flight was a month after the Soviet one, and the US had successfully returned monkeys from space before that, so arguably they were ahead technologically but less willing to use a human test subject.

It's more accurate to say that ICBM development in both the US and USSR had the unintended side-effect of giving birth to human space travel once the political benefits of using nuclear launch systems for human space travel were realized.

Well, USSR sort of had it right. This is why the US is still buying that rocket engines for new launches, designed more than 30 years ago in the "Atlantis".

And Russia buys almost everything else in US, Europe and China.

Uncontrolled military spending is a funny thing.