National Research Council (U.S.). Transportation Research Board. (1988). Research problem statements on traffic control devices. Transportation Research Board, National Research Council.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNational Research Council (U.S.). Transportation Research Board. Research Problem Statements on Traffic Control Devices. Washington, D.C: Transportation Research Board, National Research Council, 1988.
एमएलए (9वां संस्करण) प्रशस्ति पत्रNational Research Council (U.S.). Transportation Research Board. Research Problem Statements on Traffic Control Devices. Transportation Research Board, National Research Council, 1988.
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