Parity proofs of the Kochen-Specker theorem based on 60 complex rays in   four dimensions
  It is pointed out that the 60 complex rays in four dimensions associated with a system of two qubits yield over 10^9 critical parity proofs of the Kochen-Specker theorem. The geometrical properties of the rays are described, an overview of the parity proofs contained in them is given, and examples of some of the proofs are exhibited. 
Mordecai Waegell and P.K. Aravind
quant-ph