@article{1568605,
  author = {et D. Psaltis al.},
  title = {Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole},
  year = {2020},
  journal = {Physical Review Letters},
  volume = {125},
  pages = {141104},
  url = {https://ui.adsabs.harvard.edu/abs/2020PhRvL.125n1104P/abstract},
  language = {eng},
}