Robert Hastings and Bob Jacobs have an interesting book about the subject.
https://www.coasttocoastam.com/show/2019/11/17
Of course this is just one of a multitude of encounter books from various writers & researchers.
https://www.amazon.com/Confession-Hidden-Alien-Encounters-Revealed/dp/1695688856/ref=sr_1_1?qid=1574062689&refinements=p_27%3ARobert+Hastings&s=books&sr=1-1&text=Robert+Hastings
Dr. John Mack was intrigued as to who or what might be contacting some people.
https://www.pbs.org/wgbh/nova/aliens/johnmack.html
https://www.gaia.com/article/do-thousands-of-alien-abduction-accounts-add-up?
http://inexplicata.blogspot.com/2018/02/dominican-republic-ufo-and-alien.html
Is this world like someones laboratory or is is just of the many worlds that can sustain life?
http://inexplicata.blogspot.com/2011/09/highways-to-high-strangeness.html
If intelligent life has been around for the equivalent of thousands or even millions of years on other worlds, then this world would be a curiosity.
The visitations could also be from entities other dimensions or planes of cosmic existence. They might not all be of a benevolent nature.
