Christie, D. (1999). Focus on Business: Workbook / [David Christie] (New edition.). Cornelsen & Oxford.
Lua i Stíl Chicago (17ú heag.)Christie, David. Focus on Business: Workbook / [David Christie]. New edition. Berlin: Cornelsen & Oxford, 1999.
Lua MLA (8ú heag.)Christie, David. Focus on Business: Workbook / [David Christie]. New edition. Cornelsen & Oxford, 1999.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.