Flexible cross-polytopes in the Euclidean 4-space. Stachel, Hellmuth — 2000 Journal for Geometry and Graphics
Infinite number of spheres through four tangents. (Unendlich viele Kugeln durch vier Tangenten.) Stachel, Hellmuth — 1995 Mathematica Pannonica
Napoleon's theorem and generalizations through linear maps. Stachel, Hellmuth — 2002 Beiträge zur Algebra und Geometrie
Ivory's theorem in hyperbolic spaces. Stachel, Hellmuth; Wallner, Johannes — 2004 Sibirskij Matematicheskij Zhurnal
Almost-orthonormal vector systems. Haase, Dietrich; Stachel, Hellmuth — 1996 Beiträge zur Algebra und Geometrie
Generating solids by sweeping polyhedra. Elsonbaty, Ahmed; Stachel, Hellmuth — 1997 Journal for Geometry and Graphics
The development of the oloid. Dirnböck, Hans; Stachel, Hellmuth — 1997 Journal for Geometry and Graphics