TY - JOUR AU - Kiyota, Yuki AU - Tsukada, Kazumi TI - Curvature tensors and Singer invariants of four-dimensional homogeneous spaces JO - Commentationes Mathematicae Universitatis Carolinae PY - 1999 SP - 723 EP - 733 VL - 40 IS - 4 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/CMUC_1999__40_4_a9/ LA - en ID - CMUC_1999__40_4_a9 ER -