Brooks, W. (1988). Hingh impact selling. Prentice Hall.
Lua i Stíl Chicago (17ú heag.)Brooks, William. Hingh Impact Selling. New Delhi: Prentice Hall, 1988.
Lua MLA (9ú heag.)Brooks, William. Hingh Impact Selling. Prentice Hall, 1988.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.