Não informado. (1949). Annual Bulletin of Transport Statistics for Europe. United Nations, Economic Commission for Europe.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Annual Bulletin of Transport Statistics for Europe. Geneve, Suíça: United Nations, Economic Commission for Europe, 1949.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Annual Bulletin of Transport Statistics for Europe. United Nations, Economic Commission for Europe, 1949.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.