@article{CMUC_1999_40_4_a9,
     author = {Kiyota, Yuki and Tsukada, Kazumi},
     title = {Curvature tensors and {Singer} invariants of four-dimensional homogeneous spaces},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {723--733},
     year = {1999},
     volume = {40},
     number = {4},
     mrnumber = {1756548},
     zbl = {1020.53032},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1999_40_4_a9/}
}