Littlejohn, A., & Hicks, D. (1998). Cambridge english for schools: Student's book four. Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Littlejohn, Andrew, agus Diana Hicks. Cambridge English for Schools: Student's Book Four. Cambridge: Cambridge University Press, 1998.
Lua MLA (9ú heag.)Littlejohn, Andrew, agus Diana Hicks. Cambridge English for Schools: Student's Book Four. Cambridge University Press, 1998.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.