An extension of Hansen's theorem for star chains. Jan van Leeuwen — 1977 Journal für die reine und angewandte Mathematik
Computing the connected components of simple rectilinear geometrical objects in d -space Herbert Edelsbrunner; Jan Van Leeuwen; Thomas Ottmann; Derick Wood — 1984 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications