Crystal, D. (2003). English as a global language (2nd ed.). Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Crystal, David. English as a Global Language. 2nd ed. New York ; New Delhi: Cambridge University Press, 2003.
Lua MLA (8ú heag.)Crystal, David. English as a Global Language. 2nd ed. Cambridge University Press, 2003.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.