Inside Out Library · ExploreGeometrische Untersuchungen zur Theorie der Parallellinien (1887)Lobachevskiĭ, N. I. (Nikolaĭ Ivanovich), 1792-1856 · Berlin : Mayer & Müller · leaf 9Geometry, Non-Euclidean · Parallels (Geometry)Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.More pictures from Geometrische Untersuchungen zur Theorie der ParallellinienMore like this
