ETHERTON, A. (1976). Contact 4: A secondary english course. -- Ed. revisi. Longman.
Lua i Stíl Chicago (17ú heag.)ETHERTON, A.R.B. Contact 4: A Secondary English Course. -- Ed. Revisi. Kuala Lumpur: Longman, 1976.
Lua MLA (9ú heag.)ETHERTON, A.R.B. Contact 4: A Secondary English Course. -- Ed. Revisi. Longman, 1976.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.