BibTex format
@article{Hoare:2019:1751-8121/ab0b79,
author = {Hoare, B and Levine, N and Tseytlin, AA},
doi = {1751-8121/ab0b79},
journal = {Journal of Physics A: Mathematical and Theoretical},
title = {On the massless tree-level S-matrix in 2d sigma models},
url = {http://dx.doi.org/10.1088/1751-8121/ab0b79},
year = {2019}
}