TY - JOUR AU - Kowalski, Oldrich AU - Sekizawa, Masami TI - On 3-Dimensional Riemannian ...-Spaces. JO - Monatshefte für Mathematik PY - 1987 VL - 103 SP - 303 EP - 320 KW - natural operators; Riemannian metrics; pseudo-Riemannian metrics; frame bundle UR - http://eudml.org/doc/178333 ER -