Authors Year Title
Korn 1991 Threedimensionally preserved clymeniids from the Hangenberg Black Shale of Drewer (Cephalopoda, Ammonoidea; Devonian-Carboniferous boundary; Rhenish Massif).
Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1991, H.9: 553-563, fig.1-5; Stuttgart.