Messier 87

Event Horizon Telescope Collaboration (2019). First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole. The Astrophysical Journal Letters 875, L1. Event Horizon Telescope Collaboration. https://doi.org/10.3847/2041-8213/ab0ec7

@misc{cite:eht-m87-2019,
  title        = {First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole},
  author       = {Event Horizon Telescope Collaboration},
  organization = {Event Horizon Telescope Collaboration},
  howpublished = {The Astrophysical Journal Letters 875, L1},
  year         = {2019},
  doi          = {10.3847/2041-8213/ab0ec7},
  url          = {https://doi.org/10.3847/2041-8213/ab0ec7},
  note         = {First direct image of a black hole's shadow, in the galaxy M87.}
}

NASA/IPAC (Caltech) (n.d.). Messier 87 — NASA/IPAC Extragalactic Database. NASA/IPAC (Caltech). https://ned.ipac.caltech.edu/

@misc{cite:ned-galaxy-messier-87,
  title        = {Messier 87 — NASA/IPAC Extragalactic Database},
  organization = {NASA/IPAC (Caltech)},
  year         = {n.d.},
  url          = {https://ned.ipac.caltech.edu/},
  note         = {Positions, redshift, and cross-identifications for Messier 87.}
}