Visscher, Nicolaes.  "Bavariae Palatinatus vulgo die Ober-Pfaltz in subjacentes ejusdem praefecturas accuratissime divisus."  Map.  1698.  Norman B. Leventhal Map & Education Center,  https://collections.leventhalmap.org/search/commonwealth:cj82kx27h (accessed March 30, 2020).