@article{Siqueira:2007qa,
  author = "Siqueira, Christyan Assis",
  title = "{Thermofield Dynamics and Path-Integral Formalism }",
  doi = "10.22323/1.031.0044",
  journal = "PoS",
  year = 2007,
  volume = "IC2006",
  pages = "044"
}