Wikimedia
Wikipedia: Operetta
This Wikipedia site offers excellent information on the artform of the operetta, including its history, important contributors, and hyperlinked terms.
Other
Johann Strauss, Jr. 1825 1899
A biography of Johann Strauss, Jr. (1825-1899 CE) with lots of images plus an extensive list of compositions.
PBS
Classics for Kids: Johann Strauss, Jr.
This site has a short biography of Johann Strauss, Jr (1825-1899 CE) with an audio clip of the 'Tritsch-Tratsch Polka.' Click to the past radio shows to hear his music and learn more about this famous composer.