Long-term variations of available solar radiation on seasonal timescales in 1955-2006 at Tartu-Tõravere Meteorological Station, EstoniaEerme, Kalju; Kallis, Ain; Veismann, Uno; Ansko, IlmarTheoretical and applied climatology2010 / p. 371-379 : ill https://ui.adsabs.harvard.edu/abs/2010ThApC.101..371E/abstract