danupong9. (n.d.). Transportation | Effect to the
environment. Upload & Share PowerPoint presentations and documents.
Retrieved March 20, 2012, from http://www.slideshare.net/danupong9/transportation-effect-to-the-environment
Transportation and Development. (n.d.). Clackamas County,
Oregon. Retrieved March 21, 2012, from
http://www.clackamas.us/transportation/
transportation, s. t.
(n.d.). The History of Transportation. Alternative Energy, Now and In The
Future. Retrieved March 20, 2012, from
http://www.future-alternative-energy.net/history-of-transportation.html
Transport - Wikipedia, the free encyclopedia. (n.d.). Wikipedia,
the free encyclopedia. Retrieved March 20, 2012, from http://en.wikipedia.org/wiki/Transport#History