  We have performed a thorough study of the meson-meson S-waves with isospin
(I) 0 and 1/2, up to sqrt(s) ~ 2 GeV. This is the first study that includes 13
channels that have their threshold below that energy. All the resonances below
2 GeV, namely the f_0(600) or sigma, f_0(980), f_0(1370), f_0(1500), f_0(1710)
and f_0(1790) for I=0, and the K*_0(800) or kappa, K*_0(1430) and K*_0(1950)
for I=1/2, are generated. We can then extract a clear picture of the
spectroscopy, finding that the f_0(1710), together with an important
contribution to the f_0(1500), are glueballs. Another pole, which corresponds
mainly to the f_0(1370), is a pure octet I=0 state, and does not mix with the
glueball.
