Tull. (1984). Marketing research (3rd.). Macmillan.
Lua i Stíl Chicago (17ú heag.)Tull. Marketing Research. 3rd. New York: Macmillan, 1984.
Lua MLA (9ú heag.)Tull. Marketing Research. 3rd. Macmillan, 1984.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.