"Nielsen named #1 of Top 50 largest market research firms in the world; American Marketing Association 2011 Honomichl Report" (PDF).
Nielsen Holdings N.V. Ngày 13 tháng 2 năm 2013.  ^ “Nielsen named #1 of Top 50 largest market research firms in the world; American Marketing Association 2011 Honomichl Report” (PDF).