BibTex format
@article{Elder:2015:10.1103/PhysRevD.91.064002,
author = {Elder, B and Joyce, A and Khoury, J and Tolley, AJ},
doi = {10.1103/PhysRevD.91.064002},
journal = {PHYSICAL REVIEW D},
title = {Positive energy theorem for <i>P</i>(<i>X</i>, φ) theories},
url = {http://dx.doi.org/10.1103/PhysRevD.91.064002},
volume = {91},
year = {2015}
}