- Nationaal Archief
- Greg Goebel’s IN THE PUBLIC DOMAIN
- The Heritage of the Great War
- List of films in the public domain in the United States – Wikipedia
- Wikipedia
- Wikipedia:Auteursrechten – Wikipedia
- Creative Commons — Attribution-ShareAlike 3.0 Unported — CC BY-SA 3.0
- Gevechtsverslagen Meidagen 1940 online – Mei 1940, Informatie over de Tweede Wereldoorlog
- Bundesarchiv, files, photos, films and more.