Columbia subject headings:
Algae, Fossil--Congresses.
Paleobotany--Congresses.
Paleobotany--United States--Congresses.
Harvard subject headings:
Algae, Fossil--Congresses.
Paleobotany--Congresses.
Paleobotany--United States--Congresses.
Princeton subject headings:
Algae, Fossil--Congresses.
Paleobotany--Congresses.
Paleobotany--United States--Congresses.