Eleftheratos, K. Zerefos, C.S. Zanis, P. Balis, D.S. Tselioudis, G. Gierens, K. Sausen, R., A study on natural and manmade global interannual fluctuations of cirrus cloud cover for the period 1984-2004, Atmospheric Chemistry and Physics, (7), 2631-2642, 2007, European Geosciences UnionĀ (EGU), 1680-7316, 1680-7324