Tien-Yien Li Xiaoshen Wang Counterexamples to the Connectivity Conjecture of the Mixed Cells. 515-521 1998 20 Discret. Comput. Geom. 4 https://doi.org/10.1007/PL00009399 https://www.wikidata.org/entity/Q122920123 db/journals/dcg/dcg20.html#LiW98