1649 Mapa de Grolla Obsessa et Expugnata (Expvgnata) por Joan y Willem Blaeu
English: Map of the Siege of Grol (Groenlo) in 1627 by Frederick Henry, Prince of Orange. Map by Willem and Joan Blaeu, 1649. Engraved by Hugo de Groot, and published in the "Atlas von Loon" by Blaeu in Amsterdam in 1629.