Hill, F. E., & Williams, W. (1941). Radio's listening groups: The United States and Great Britain. Columbia University Press.

Hill, Frank Ernest, and W.E Williams. Radio's Listening Groups: The United States and Great Britain. New York: Columbia University Press, 1941.

Hill, Frank Ernest, and W.E Williams. Radio's Listening Groups: The United States and Great Britain. Columbia University Press, 1941.