I was going to suggest The Moon is a Harsh Mistress - Robert Heinlein but Can't find a legal eBook version of it.
I'll still like to suggest one of his books, Either
Stranger in a Strange Land - Robert Heinlein
Double Star - Robert Heinlein
Which are really good reads, and reasonably good introductions to his work (though Moon is obviously the best
Otherwise, I'll suggest one of the SF golden oldies by Asimov like
Foundation by Isaac Asimov