Kalogiros J., Anagnostou M. N., Anagnostou E. N., Montopoli M., Picciotti E., and Marzano F. S.: Optimum estimation of rain microphysical parameters using X-band dual-polarization radar observables, IEEE Transactions on Geoscience and Remote Sensing Vol Doi: 10.1109/TGRS.2012.2211606, 2012