Columbia subject headings:
Harvard subject headings:
Carbon cycle (Biogeochemistry)
Carbon cycle (Biogeochemistry)--Environmental aspects.
Energy development--Environmental aspects
Nature--Effect of human beings on
Nitrogen cycle--Environmental aspects.
Nitrogen cycle.
Sulfur cycle.
Sulfur--Environmental aspects.
Princeton subject headings:
Carbon cycle (Biogeochemistry)--Environmental aspects.
Energy development--Environmental aspects.
Nature--Effect of human beings on.
Nitrogen cycle--Environmental aspects.
Sulfur--Environmental aspects.