Columbia subject headings:
Harvard subject headings:
Geology, Stratigraphic--Cambrian
Geology, Stratigraphic--Precambrian
Paleontology--Cambrian
Paleontology--Precambrian
Princeton subject headings:
Geology, Stratigraphic--Cambrian.
Geology, Stratigraphic--Precambrian.
Paleontology--Cambrian.
Paleontology--Precambrian.