HI absorption in radio galaxies
  Twenty-two powerful radio galaxies have been searched for HI absorption. We find the highest probability of detecting HI in absorption among narrow-line compact (or small) galaxies or galaxies with indication of richer interstellar medium (i.e. with ongoing or recent star-formation). We discuss the difficulty in the interpretation of the origin of the HI absorption due to the uncertainty in the systemic velocity of the galaxies. 
R. Morganti, T.A. Oosterloo, G. van Moorsel, C.N. Tadhunter, N.   Killeen