@article{articlee1d17ec2,
title   = {Thermal operator representation of finite temperature graphs},
author = {Brandt, Fernando Tadeu Caldeira and Das, Ashok and Espinosa, Olivier and Frenkel, Josif and Perez, Silvana},
year = {2005},
doi = {10.1103/physrevd.73.065010},
journal   = {Physical Review D}
}