Columbia subject headings:
Computer bulletin boards.
Computer networks.
Environmental protection--Automation.
Environmental protection--Computer programs.
Harvard subject headings:
Environmental protection--Information services--Directories.
Environmental sciences--Information services
Information storage and retrieval systems--Environmental protection--Directories.
Princeton subject headings:
Computer bulletin boards.
Environmental policy--Data processing.
Environmental protection--Data processing.
Information storage and retrieval systems--Environmental policy.
Information storage and retrieval systems--Environmental protection.