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