1. H. Elvang and Y.-t. Huang, “Scattering amplitudes,” arXiv:1308.1697 [hep-th] (2013).
2. S. Weinzierl, Phys. Rep. 676, 1–101 (2017).
3. A. van Hameren, J. High Energy Phys. 07, 138 (2014).
4. A. van Hameren and M. Serino, J. High Energy Phys. 07, 010 (2015).
5. K. Kutak, A. Hameren, and M. Serino, J. High Energy Phys. 02, 009 (2017).