  e+e- Experiments producing charmonium are reviewed. It is found that the
contribution of the continuum amplitude via virtual photon was neglected in
almost all the experiments and the channels analyzed. It is shown that the
contribution of the continuum part may affect the final results significantly
in psi(2S) and psi(3770) decays, while the interference between continuum and
resonance amplitudes may even affect the J/psi decays as well as the psi(2S)
and psi(3770). This should be considered in analyzing the "rho-pi puzzle"
between J/psi and psi(2s) decays, and the difference between inclusive hadron
and DDbar cross sections in psi(3770) decays.
