FERBER ROBERT EDT. (1974). HANDBOOK OF MARKETING RESEARCH. MCGRAW-HILL.
Lua i Stíl Chicago (17ú heag.)FERBER ROBERT EDT. HANDBOOK OF MARKETING RESEARCH. NEW YORK: MCGRAW-HILL, 1974.
Lua MLA (9ú heag.)FERBER ROBERT EDT. HANDBOOK OF MARKETING RESEARCH. MCGRAW-HILL, 1974.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.