If a primary source is also a historical map, there should be a checkbox to check it and also a textbox for the link.
On the map page, the system should show only sources that are historical maps and are contained in the BBox. The BBox is the smaller rectangle containing all the BBoxes of the linked islands.
If a primary source is also a historical map, there should be a checkbox to check it and also a textbox for the link.
On the map page, the system should show only sources that are historical maps and are contained in the BBox. The BBox is the smaller rectangle containing all the BBoxes of the linked islands.