Proceratocephala terribilis bituberculata
Upper Ordovician trilobites from Poland and some related forms from Bohemia and Scandinavia [Trylobity gorno-ordowiokie polski i pewne formy zblizone z Czech i Skandynawii]. Palaeontologia Polonica, No. 11 1960: i-vi, 1-198. 107 [Zoological Record Volume 97]