Der Kunstdenkmäler der Stadt Duisburg und der Kreise Mülheim a.d. Ruhr und Ruhrort
A German art-historical survey of monuments in Duisburg and the nearby districts of Mülheim an der Ruhr and Ruhrort, published in Düsseldorf in 1893 by Paul Clemen and aimed at scholars and regional heritage readers. The pictures are plain black-and-white line drawings of castles, churches and cloisters, plus a ground plan, drawn with dense hatching and clean outlines that a designer could use as reference for architectural linework and period building forms.
