BIBER, D. (2002). Longman Student Grammar of Spoken and Written English. Longman.
Lua i Stíl Chicago (17ú heag.)BIBER, Douglas. Longman Student Grammar of Spoken and Written English. Longman, 2002.
Lua MLA (8ú heag.)BIBER, Douglas. Longman Student Grammar of Spoken and Written English. Longman, 2002.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.