Peaucellier–Lipkin inversor
Tangent developable of a quartic space curve
Ruled surfaces of degree 4 by Rohn
Singularity in the origin
Envelopes of surface normals
Accompanying ruled surfaces
Extremal polyhedra by Brehm
Kartonmodelle von Flächen 2. Ordnung
Brill/Schilling, Series 1
Brill/Schilling, Series 3
Brill/Schilling, Series 2