Não informado. Transport economics. Interstate Commerce Commission, Bureau of Transport Economics and Statistics.
Chicago-referens (17:e uppl.)Não informado. Transport Economics. Washington: Interstate Commerce Commission, Bureau of Transport Economics and Statistics.
MLA-referens (8:e uppl.)Não informado. Transport Economics. Interstate Commerce Commission, Bureau of Transport Economics and Statistics.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.