[Groningen]. "Delf Siil."

Engr. bird's eye plan, 40,2x51,8 cm., from BLAEU, Townbooks, ±1650. "Bellingwolder-Schans." "Bourtang." Two engr. bird's-eye plans on 1 leaf, 40,8x25 and 40,8x25,2 cm., from the same work.

AND 6 other similar fortification plans on 5 lvs.: "Bourtang", "Bellingwolder Schans", "Langacker Schans" (2x), "Delfzil" and "Winschoten".