TULL DONALD S. (2009). MARKETING RESEARCH: MEASUREMENT AND METHOD (6TH.). PRENTICE HALL OF INDIA.
Lua i Stíl Chicago (17ú heag.)TULL DONALD S. MARKETING RESEARCH: MEASUREMENT AND METHOD. 6TH. NEW DELHI: PRENTICE HALL OF INDIA, 2009.
Lua MLA (9ú heag.)TULL DONALD S. MARKETING RESEARCH: MEASUREMENT AND METHOD. 6TH. PRENTICE HALL OF INDIA, 2009.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.