Não informado. (2001). Bibliography. National Research Council, Transportation Research Board.
Chicago-referens (17:e uppl.)Não informado. Bibliography. Washington: National Research Council, Transportation Research Board, 2001.
MLA-referens (8:e uppl.)Não informado. Bibliography. National Research Council, Transportation Research Board, 2001.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.