BibTex format
@article{Kitching:2017:10.1103/PhysRevD.95.063522,
author = {Kitching, TD and Heavens, AF},
doi = {10.1103/PhysRevD.95.063522},
journal = {PHYSICAL REVIEW D},
title = {Unequal-time correlators for cosmology},
url = {http://dx.doi.org/10.1103/PhysRevD.95.063522},
volume = {95},
year = {2017}
}