Tregidgo, P. S. (1979). English grammar in practice. Longman.
Lua i Stíl Chicago (17ú heag.)Tregidgo, P. S. English Grammar in Practice. Harlow: Longman, 1979.
Lua MLA (9ú heag.)Tregidgo, P. S. English Grammar in Practice. Longman, 1979.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.