Jacob Steiner's Gesammelte Werke (AMS Chelsea Publishing)

These volumes contain the Collected Works of Jakob Steiner (1796-1863), one of the greatest contributors to projective geometry. He is famous for the Steiner surface, which has a double infinity of conic sections on it, for the Poncelet-Steiner theorem, which shows that only one given circle and a straight edge are required for Euclidean constructions, and for the Steiner circles, which are used in studying the properties of conformal transformations. The text is in German.