Erkelens (Fortification of the Town Erkelenz)
Joan Blaeu (1596-1673
circa 1650 <div style="display: none;">date QS:P,+1650-00-00T00:00:00Z/9,P1480,Q5727902</div>
Novum ac magnum theatrum urbium Belgicae, about 1650, Scanvorlage In: Heimatkalender des Kreises Heinsberg 2003