Spectroscopic evidence of Multiple Stellar Populations in Globular
  Clusters
  Galactic globular clusters are not simple stellar populations. And nothing is
simple in their study, basically because we try to reconstruct chains of events
that occurred at redshift z > 2-3 by observing these objects at z=0, after a
Hubble time. Fortunately, spectroscopy offers a magnifying lens: differences of
tens or hundreds of Myrs between stellar generations are translated into
differences in abundances up to a full dex. I will review the complex pattern
emerging by the combined efforts of different groups, focusing on the chemical
signatures of multiple populations in globular clusters.
