That's in the article. In the US, the copyright term (for the relevant period) was the date they were published plus n years. In (most of) Europe, it's the li

That's in the article. In the US, the copyright term (for the relevant period) was the date they were published plus n years. In (most of) Europe, it's the life of the author plus n years. So for a book published 50 years before the author died, the term expires in the US long before it does in (most of) Europe. (This has since changed in the US, but did not apply retroactively. So published+n still applies to works published before the change to life+n)