Perspective Published on 21 Dec 2017 Circum-Galactic Medium in the Halo of Quasars in Extragalactic Astronomy Riccardo OttolinaRenato FalomoAldo TrevesMichela UslenghiJari K. KotilainenRiccardo ScarpaEmanuele Paolo Farina Frontiers in Astronomy and Space Sciences doi 10.3389/fspas.2017.00061 2,973 views 1 citation