@article{paper1972,
  title={Methods of Modern Mathematical Physics},
  author={},
  year={1972},
  journal={Elsevier eBooks},
  doi={10.1016/b978-0-12-585001-8.x5001-6},
  url={https://doi.org/10.1016/b978-0-12-585001-8.x5001-6}
}