391705 Langan, J. (1985). English skills. New York : McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)391705 Langan, John. English Skills. New York : McGraw-Hill, 1985.
Lua MLA (9ú heag.)391705 Langan, John. English Skills. New York : McGraw-Hill, 1985.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.