@article{1435177,
  author = {et The EHT Collaboration al.},
  title = {First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole},
  year = {2019},
  journal = {ApJL},
  volume = {875},
  pages = {6},
  url = {https://iopscience.iop.org/article/10.3847/2041-8213/ab1141},
  language = {eng},
}