Columbia subject headings:
Marine pollution--Environmental aspects--Netherlands--Waddenzee--Congresses.
Tidal flat ecology--Netherlands--Waddenzee--Congresses.
Harvard subject headings:
Marine ecology--Netherlands--Waddenzee--Congresses.
Marine pollution--Netherlands--Waddenzee--Congresses.
Organic water pollutants--Netherlands--Waddenzee--Congresses.
Tidal flat ecology--Netherlands--Waddenzee--Congresses.
Princeton subject headings: