I have a deep love for the stars and so below I will link you to some really cool resourceful sites that I use which teaches on black holes and astronomy in general.
(Free Google art)
Here is a very good link to one of NASA’s sites that allows one to really learn a lot in one place about black holes and how their growth may affect their host galaxies.
When one wants information about space-time and or how gravitational waves effect our earth, this is a very good site and its full of new discoveries geographically.
This site talks about the possibilities of a black hole apocalypse and it gives a very informative video about what one could expect if it were to happen to earth.
This site allows scientists to come together globally with common monthly information about discoveries and calculations. The monthly letter for April 2018, talks about black holes. Oxford University publishes these monthly articles.