"Commuter Rail Safety Study". Office of Safety and Security, Federal Transit Administration, United States Department of Transportation. november 2006. Arkiveret fra originalen 20. marts 2009. Hentet 31. juli 2008.
"FTA-MA-26-0052-04-1 Rails-with-Trails: Lessons Learned". Federal Highway Administration, Federal Railroad Administration, Federal Highway Traffic Safety Administration, Federal Transit Administration, United States Department of Transportation. august 2002. Arkiveret fra originalen 20. november 2008. Hentet 31. juli 2008.
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"Commuter Rail Safety Study". Office of Safety and Security, Federal Transit Administration, United States Department of Transportation. november 2006. Arkiveret fra originalen 20. marts 2009. Hentet 31. juli 2008.
"FTA-MA-26-0052-04-1 Rails-with-Trails: Lessons Learned". Federal Highway Administration, Federal Railroad Administration, Federal Highway Traffic Safety Administration, Federal Transit Administration, United States Department of Transportation. august 2002. Arkiveret fra originalen 20. november 2008. Hentet 31. juli 2008.