1. A. Hodges, Eliminating spurious poles from gauge-theoretic amplitudes, JHEP 05 (2013) 135 [ arXiv:0905.1473 ] [ INSPIRE ].
2. L. Mason and D. Skinner, Dual superconformal invariance, momentum twistors and grassmannians, JHEP 11 (2009) 045 [ arXiv:0909.0250 ] [ INSPIRE ].
3. N. Arkani-Hamed, F. Cachazo and C. Cheung, The grassmannian origin of dual superconformal invariance, JHEP 03 (2010) 036 [ arXiv:0909.0483 ] [ INSPIRE ].
4. L. Mason and D. Skinner, Amplitudes at weak coupling as polytopes in AdS 5, J. Phys. A 44 (2011) 135401 [ arXiv:1004.3498 ] [ INSPIRE ].
5. A. Hodges, Crossing and twistor diagrams, in Twistor Newsletter 5, Mathematical Institute, University of Oxford, U.K. (11 July, 1977), reprinted in Further Advances in twistor theory, L.P. Hughston and R.S. Ward eds., Chapman & Hall/CRC, U.S.A. (1979).