Mercedes Sosa - Where to start?

I was listening to some speakers at an audition a couple of weeks ago, and one of the tracks played during the warm up was by Mercedes Sosa,  It was a haunting and beautiful track, but I did not at the time ask the title or the album.  I could ask now, but I am not sure they would recall.

I have looked to buy some of her music, but she has recorded over 40 albums.  Can any one recommend a creates hist or anthology type collection, that would give a taste of her wonderful voice?

Many thanks,

Andrew