Columbia subject headings:
Geology, Stratigraphic--Carboniferous.
Geology, Stratigraphic--Devonian.
Paleontology--Carboniferous.
Paleontology--Devonian.
Harvard subject headings:
Princeton subject headings:
Geology, Stratigraphic--Carboniferous.
Geology, Stratigraphic--Devonian.
Paleontology--Carboniferous.
Paleontology--Devonian.