Kaskaoutis D.G., Kambezidis H.D., Adamopoulos A.D. and Kassomenos P.: Comparison between experimental data and modeling estimates of aerosol optical depth over Athens, Greece, Journal of Atmospheric & Solar-Terrestrial Physics Vol 68(11) p.1167-1178 Doi: 10.1016/j.jastp.2006.02.011, 2006