A handy site for all things broadcast, both radio and television. http://www.museum.tv/eotvsection.php?entrycode=soapopera
Handier references, at least for radio:
John Dunning, On the Air: The Encyclopedia of Old-Time Radio.
Leonard Maltin, The Great American Broadcast.
Jordan R. Young, The Laugh Crafters: Comedy Writing in Radio and Television's Golden Age.
James Thurber, The Beast in Me, which includes his staggering, five-part New Yorker observation and analysis of the radio soaps, "Soapland."
Gerald Nachman, Raised on Radio.
Fred Allen, Treadmill to Oblivion (freshly republished).
In my Amazon “to buy” list.
# A Tower in Babel: A History of Broadcasting in the United States To 1933 , Oxford University Press, 1966.
# The Golden Web: A History of Broadcasting in the United States 1933-1953, Oxford University Press, 1968.
# The Image Empire: A History of Broadcasting in the United States from 1953, Oxford University Press, 1970.
http://en.wikipedia.org/wiki/Erik_Barnouw