Boyd, H. W., & Westfall, R. (1972). Marketing research: Text and cases (3rd ed.). Irwin.
Lua i Stíl Chicago (17ú heag.)Boyd, Harper W., agus Ralph Westfall. Marketing Research: Text and Cases. 3rd ed. Illinois: Irwin, 1972.
Lua MLA (9ú heag.)Boyd, Harper W., agus Ralph Westfall. Marketing Research: Text and Cases. 3rd ed. Irwin, 1972.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.