A bibliotheek is a library. When doing Dutch research, keep in mind that most genealogical collections are held at archives, not libraries like in some other countries.

Library of the Court of Justice, The Hague. Credits: Rijksdienst voor Cultureel Erfgoed (CC-BY-SA)

This is a beautiful library! When was it built? Is it open to the public?
At that point in time, the Court of Justice was located in a former palace of Prince Frederik that was built from 1827 to 1830. I believe it was destroyed when The Hague was bombed in World War II.