@article{therneau2000,
  title={Modeling Survival Data: Extending the Cox Model},
  author={Terry M. Therneau and Patricia M. Grambsch},
  year={2000},
  journal={Statistics in the health sciences},
  doi={10.1007/978-1-4757-3294-8},
  url={https://doi.org/10.1007/978-1-4757-3294-8}
}