@article {1435168, title = {First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole}, journal = {ApJL}, volume = {875}, year = {2019}, pages = {1}, url = {https://iopscience.iop.org/article/10.3847/2041-8213/ab0ec7}, author = {The EHT Collaboration et al.} }