^Nielsen Business Media, Inc. (9 April 1977). Billboard. Nielsen Business Media, Inc. pp. 50–. ISSN0006-2510. {{cite book}}: |author= has generic name (help)
^Nielsen Business Media, Inc. (30 June 1973). Billboard. Nielsen Business Media, Inc. pp. 57–. ISSN0006-2510. {{cite book}}: |author= has generic name (help)