@misc{guo2022bubble,
  title={Bubble in the Whale: Identifying the Optical Counterparts and Extended Nebula for the Ultraluminous X-ray Sources in NGC 4631},
  author={Jing Guo and Jianfeng Wu and Hua Feng and Zheng Cai and Ping Zhou and Changxing Zhou and Shiwu Zhang and Junfeng Wang and Mouyuan Sun and Wei-Min Gu and Shan-Shan Weng and Jifeng Liu},
  year={2022},
  eprint={2301.00022},
  archivePrefix={arXiv},
  primaryClass={astro-ph.HE},
  doi={10.3847/1538-4357/acaddd},
  url={https://arxiv.org/abs/2301.00022}
}