Não informado. (2021). Annual Bulletin of Transport Statistics for Europe and North America. United Nations.
Lua i Stíl Chicago (17ú heag.)Não informado. Annual Bulletin of Transport Statistics for Europe and North America. New York: United Nations, 2021.
Lua MLA (8ú heag.)Não informado. Annual Bulletin of Transport Statistics for Europe and North America. United Nations, 2021.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.