Lehrbuch der projektivischen (neuren) Geometrie; synthetische Geometrie, Geometrie der Lage
A German textbook of projective (synthetic) geometry by J. Sachs, published in Stuttgart by J. Maier in 1900 for university and technical-school students. The 142 line figures show conics, tangents, pencils of rays and polar constructions, built from solid, dashed and dash-dot lines with small circles, crosses and italic letter labels usable as diagram vocabulary.
