Urbanek, Adam; Towe, Kenneth M.
(1975)
The ultrastructure of the organic periderm in <i>Didymograptus</i> sp. (Lower Ordovician), <i>Pristiograptus dubius</i> (Suess), and in the retiolitid <i>Holoretiolites mancki</i> (Münch) (both Upper Silurian), isolated ...