Columbia subject headings:
Transportation and state--Denmark.
Transportation and state--Netherlands.
Transportation and state--Sweden.
Transportation--Environmental aspects--Denmark.
Transportation--Environmental aspects--Netherlands.
Transportation--Environmental aspects--Sweden.
Harvard subject headings:
Transportation and state--Denmark.
Transportation and state--Europe--Case studies.
Transportation and state--Netherlands.
Transportation and state--Sweden.
Transportation--Environmental aspects--Denmark.
Transportation--Environmental aspects--Europe--Case studies.
Transportation--Environmental aspects--Netherlands.
Transportation--Environmental aspects--Sweden.
Princeton subject headings:
Transportation and state--Denmark.
Transportation and state--Netherlands.
Transportation and state--Sweden.
Transportation--Environmental aspects--Denmark.
Transportation--Environmental aspects--Netherlands.
Transportation--Environmental aspects--Sweden.