Columbia subject headings:
Harvard subject headings:
Constructed wetlands--Congresses.
Sewage disposal in rivers, lakes, etc.--Congresses.
Sewage--Environmental aspects--Congresses.
Wetland ecology--Congresses
Princeton subject headings:
Sewage disposal in rivers, lakes, etc.--Congresses.
Sewage--Environmental aspects--Congresses.
Wetland ecology--Congresses.