Stanford University
Stanford Encyclopedia: j.j. Thomson and the Electron
This site from the Stanford Encyclopedia of Philosophy offers a historical review of the discovery of the electron by J. J. Thomson and how he came to his conclusions performing experiments witha cathode ray tube.
Frostburg State University
General Chemistry Online: Discovery of the Electron
This site from General Chemistry Online of the Frostburg State University provides an explanation of Thomson's discovery of the electron using a cathode ray tube and also his plum cake model of the atom.