Columbia subject headings:
Geology--Netherlands--Periodicals.
Geology--Periodicals.
Mines and mineral resources--Periodicals.
Harvard subject headings:
Geology--Netherlands--Periodicals.
Geology--Periodicals
Mines and mineral resources--Periodicals
Princeton subject headings:
Geology--Netherlands--Periodicals.
Geology--Periodicals.
Mines and mineral resources--Periodicals.
Periodicals.