Black holes: Cosmic signal rattles Earth after 7 billion years - BBC News
https://www.bbc.com/news/science-environment-53993937LIGO and Virgo spotted the first confirmed midsize black hole | Science News
https://www.sciencenews.org/article/physics-gravitational-waves-midsize-black-hole-collision-ligo-virgoMost massive black-hole merger results in powerful ripple in space-time
https://www.inverse.com/science/gravitational-wave-signal-most-massive-black-hole-mergerThese Black Holes Shouldn’t Exist, but There They Are - The New York Times
https://www.nytimes.com/2020/09/02/science/black-hole-astronomy-physics.html