Central Transportation Planning Staff. CHAPTER 5: Priorities for Achieving a State of Good Repair(PDF). The Program for Mass Transportation. Massachusetts Bay Transportation Authority: 5-2. December 2009 [2019-04-21]. (原始内容存档(PDF)于2019-12-08).
Central Transportation Planning Staff. CHAPTER 5: Priorities for Achieving a State of Good Repair(PDF). The Program for Mass Transportation. Massachusetts Bay Transportation Authority: 5-2. December 2009 [2019-04-21]. (原始内容存档(PDF)于2019-12-08).