Columbia subject headings:
Ecology--Dictionaries.
Environmental protection--Dictionaries.
Nature--Effect of human beings on--Dictionaries.
Harvard subject headings:
Ecology--Dictionaries
Ecology--Encyclopedias.
Environmental protection--Dictionaries
Environmental sciences--Encyclopedias
Nature--Effect of human beings on--Dictionaries.
Princeton subject headings:
Dictionaries.
Ecology--Dictionaries.
Environmental protection--Dictionaries.
Nature--Effect of human beings on--Dictionaries.