FREEMANTLE, D. (1992). Incredible Customer Service. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)FREEMANTLE, David. Incredible Customer Service. McGraw-Hill, 1992.
Lua MLA (8ú heag.)FREEMANTLE, David. Incredible Customer Service. McGraw-Hill, 1992.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.