Kress, G. (1982). Marketing Research / George Kress. Prentice Hall.
Lua i Stíl Chicago (17ú heag.)Kress, George. Marketing Research / George Kress. Prentice Hall, 1982.
Lua MLA (8ú heag.)Kress, George. Marketing Research / George Kress. Prentice Hall, 1982.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.