* J. Bokowski, J. Richter & B. Sturmfels: “Nonrealizability proofs in computational geometry”. Discrete Comput. Geometry, 5 (1990) 333–350. | * J. Bokowski, J. Richter & B. Sturmfels: “Nonrealizability proofs in computational geometry”. Discrete Comput. Geometry, 5 (1990) 333–350. |