E. D. Kallitsis, A. V. Karakasiliotis, G. E. Boultadakis, and P. V. Frangos, “A Fully Automatic Autofocusing Algorithm for Post-processing ISAR Imaging based on Image Entropy Minimization”, ELEKTRON ELEKTROTECH, vol. 110, no. 4, pp. 125-130, Jun. 2011.