Não informado. (1981). Direction of Trade Statistics. International Monetary Fund.
Lua i Stíl Chicago (17ú heag.)Não informado. Direction of Trade Statistics. Washington: International Monetary Fund, 1981.
Lua MLA (8ú heag.)Não informado. Direction of Trade Statistics. International Monetary Fund, 1981.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.