On 4/3/07, peter green plugwash@p10link.net wrote:
but how do you know that those books don't contain extracts from other copyright works that *have* been renewed?
Books generally state if contents have been published before in other forms. Photographs and to a lesser degree illustrations may be problematic, however; these are normally attributed, but it's generally quite hard to tell if photographs have been independently copyrighted, AFAIK.
Some photographs were submitted to the Library of Congress in the US as part of copyright registration of a photograph collection, but I suspect this was far from a universal copyright. Since in pre Berne Convention US copyright law things were not 'born copyrighted' but had to be registered and published with a copyright claim, in most cases there is no independent photograph copyright, however.
-Matt