Virtual infrastructure planning: The GEYSERS approach - Tzanakaki, A.; Anastasopoulos, M. P.; Georgakilas, K.; Garcia-Espin, J.A.; Riera, J.F.; Figuerola, S.; Ghijsen, M.; Demchenko, Y.; De Laat, C.T.A.M.; Vicat-Blanc, P.; Soudan, S.; Anhalt, F.; et al. (2012 Future Network and Mobile Summit, FutureNetw 2012, 2012)