@article{purvis1982,
  title={A full coupled-cluster singles and doubles model: The inclusion of disconnected triples},
  author={George D. Purvis and Rodney J. Bartlett},
  year={1982},
  journal={The Journal of Chemical Physics},
  doi={10.1063/1.443164},
  url={https://doi.org/10.1063/1.443164}
}