Columbia subject headings:
Harvard subject headings:
Earth sciences--Study and teaching (Higher)--Canada--Statistics--Periodicals.
Earth sciences--Study and teaching (Higher)--United States--Statistics--Periodicals.
Geology--Study and teaching (Higher)--Canada--Statistics--Periodicals.
Geology--Study and teaching (Higher)--United States--Statistics--Periodicals.
School enrollment--Canada--Statistics--Periodicals.
School enrollment--United States--Statistics--Periodicals.
Princeton subject headings:
Earth sciences--Study and teaching (Higher)--Canada.
Earth sciences--Study and teaching (Higher)--United States.