An auteur is an author.
Before the introduction of modern copyright laws, publishers could sometimes obtain a patent, giving them exclusive rights to publish a book. You may find these patents in court records. The first real copyright law in the Netherlands dates from 1817.
The current copyright law is the Auteurswet 1912. A work is protected by copyright for 70 years after the death of an author (counted from January 1st in the year after the death). Work that was published anonymously or by an organization becomes in the public domain 70 years after publication. There are exceptions to these rules, so consult the law for details.