@article{DeDomenico:56192,
      author        = "De Domenico, M. and Solé-Ribalta, A. and Cozzo, E. and
                       Kivelä, M. and Moreno, Y. and Porter, M.A. and Gómez, S.
                       and Arenas, A.",
      title         = "{Mathematical formulation of multilayer networks}",
      year          = "2014",
}