5The Port Authority of New York & New Jersey.Truck replacement program[EB/OL].http://www.panynj.gov/truckers- resources/truck- re- placement.html,2012-03 -22.
6The port of Long Beach. Clean trucks[EB/OL].http://www.polb.com/civ- ea/filebankPolobdload.asp?BloblD=3759,2012-03-22.