@article{Ceballos:130850,
      author        = "Ceballos, M. and Otal, A. and Ugarte, L. and Villacampa,
                       R.",
      title         = "{Invariant Complex Structures on 6-Nilmanifolds:
                       Classification, Frölicher Spectral Sequence and Special
                       Hermitian Metrics}",
      year          = "2016",
}