Blankenstein Castle in Hattingen, north-western aspect
Fülle, Barmen
published 1909
Albert Ludorff (Ed.), <i>Die Bau- und Kunstdenkmäler des Kreises Hattingen</i>, Münster : Schöningh, 1909, p. 23 (<a rel="nofollow" class="external text" href="https://archive.org/stream/bauundkunstdenkm29ludouoft#page/23/mode/1up">online</a>)