Columbia subject headings:
Hazardous wastes--Environmental aspects--Congresses.
Radioactive wastes--Environmental aspects--Congresses.
Sewage sludge digestion--Environmental aspects--Congresses.
Harvard subject headings:
Princeton subject headings:
Hazardous wastes--Environmental aspects--Congresses.
Radioactive wastes--Environmental aspects--Congresses.
Sewage sludge digestion--Environmental aspects--Congresses.