Columbia subject headings:
Harvard subject headings:
Mammoths
Mastodons
Paleontology--Illinois
Paleontology--Iowa
Princeton subject headings:
Mammoths--Illinois.
Mammoths--Iowa.
Mastodons.
Paleontology--Illinois.
Paleontology--Iowa.
Paleontology--Pleistocene.
Proboscidea (Mammals), Fossil--Illinois.
Proboscidea (Mammals), Fossil--Iowa.