@article{VERRONEN08_GRL,
   author = "P. T. Verronen and B. Funke and M. L{\'o}pez-Puertas and
             G. P. Stiller and T. von Clarmann and N. Glatthor and
             C.-F. Enell and E. Turunen and J. Tamminen",
   title  = "About the increase of {HNO}$_3$ in the stratopause region
             during the {H}alloween 2003 solar proton event",
   journal= "Geophys. Res. Lett.",
   volume = "35",
   eid    = "L20809",
   doi    = "10.1029/2008GL035312",
   year   = "2008"   }