Prevalence of High X-Ray Obscuring Columns among AGNs that Host HO MasersDOI: info:10.1086/592782v. 686IOP PublishingL13–L16
Greenhill, Lincoln J., Tilak, Avanti, and Madejski, Grzegorz. 2008. "Prevalence of High X-Ray Obscuring Columns among AGNs that Host H2O Masers." The Astrophysical Journal Letters, 686 L13–L16. https://doi.org/10.1086/592782.