Nielsen Business Media, Inc. (13 March 1993). Billboard. Nielsen Business Media, Inc. ISSN0006-2510. Retrieved 11 April 2012. {{cite book}}: |author= has generic name (help)
Nielsen Business Media, Inc. (13 March 1993). Billboard. Nielsen Business Media, Inc. ISSN0006-2510. Retrieved 11 April 2012. {{cite book}}: |author= has generic name (help)