Columbia subject headings:
Harvard subject headings:
Microbial metabolism--Congresses.
Nitrogen cycle--Congresses.
Nitrogen--Fixation--Congresses
Sulfur cycle--Congresses.
Sulfur--Metabolism--Congresses.
Princeton subject headings:
Microbial metabolism--Congresses.
Nitrogen cycle--Congresses.
Nitrogen--Fixation--Congresses.
Sulfur cycle--Congresses.
Sulfur--Metabolism--Congresses.