An enhanced HNO₃ second maximum in the Antarctic midwinter upper stratosphere 2003 - Stiller, G. P.; Mengistu Tsidu, G.; Clarmann, T. von; Glatthor, N.; Höpfner, M.; Kellmann, S.; Linden, A.; Ruhnke, R.; Fischer, H.; Lopez-Puertas, M.; Funke, B.; Gil-Lopez, S. (Journal of Geophysical Research, 2005)