Thornton, D. Toohey, L. Avallone, A. G. Hallar, H. Harder, M. Martinez, J. B. Simpas, W. H. Brune, M. Koike, Y. Kondo, N. Takegawa, B. E. Anderson, and M. Avery (2005), Variability of active chlorine in the lowermost Arctic stratosphere, J. Geophys. Res., 110, D22304, doi:10.1029/2004JD005580.