00320nam a2200097Ia 4500008004100000100001800041245007700059245001900136260000900155856005800164160531s9999    xx            000 0 und d  aKragh, Helge.  aGeometry and Astronomy: Pre-Einstein Speculations of Non-Euclidean Space  cby Helge Kragh  c2012  uhttps://arxiv.org/ftp/arxiv/papers/1205/1205.4909.pdf