References
- M. V. Lowson, "Surfaee transport history in the UK: analysis and projections," Proc. Instn Civ, Engrs Iransp., 1998, 129. Feb., 14-19
- William Vandersteel, U.S. Patent No. 4,458,602, 1980
- Vance, L., Maitson, P., (1994), Tube Transportation, US Dept of Transportation, Volpe National Transportation Systems Center, Feb.)
- http://www.tubexpress.com/index.htm
- http://www.cargocap.de/html_en/strasse_01.html
- http://et3.com/index.html
- http://faculty.washington.edu/-jbs/itrans/flextaxi.htm
- http://www.tubeway.de