C.  Bouras, Papazois, A., Kokkinos, V., and Tseliou, G., ?Fractional Frequency Reuse in Integrated Femtocell/Macrocell Environments?, in 11th International Conference on Wired/Wireless Internet Communications (WWIC 2013), Saint - Petersbourg, Russia, 2013, pp.  229 - 240.