1959  Patteisky, p.57, fig.18a, 18b, combined section of  Ruhr region.
     1995  Kullmann & Nikolaeva, p.127, fig.7.
     1998  Nikolaeva & Kullmann: 125, Section: fig.3.
     2005  Kullmann: 27, Section: fig.1 lower part: fig.1 A, B.

Fig. LOC6178.