https://murderpedia.org/male.F/f/ferguson-colin.htm
https://murderpedia.org/male.R/r/rifkin-joel.htm
https://www.biography.com/crime-figure/joel-rifkin
https://abcnews.go.com/blogs/headlines/2013/03/how-police-identified-severed-head-after-24-year-mystery
https://www.foxnews.com/us/severed-head-found-in-new-jersey-in-89-idd-linked-to-serial-killer
https://en.wikipedia.org/wiki/Joel_Rifkin
https://www.wcax.com/2021/06/08/10-years-since-vermont-couple-kidnapped-murdered-by-serial-killer/
https://www.oxygen.com/method-of-a-serial-killer/crime-time/serial-killer-israel-keyes-suicide-note
https://archive.ph/20120913051348/http://www.ktva.com/home/outbound-xml-feeds/Police-Explain-Why-They-Wont-Release-Video-of-Koenig-Abduction-138943419.html#selection-1107.0-1107.219
https://www.biography.com/crime-figure/israel-keyes#:~:text=Israel%20Keyes%20was%20an%20American,was%20arrested%20in%20March%202012.
https://thebrag.com/israel-keyes-serial-killer/
https://www.youtube.com/watch?v=TeRwScNWUZc
https://www.leeds-live.co.uk/news/leeds-news/yorkshire-ripper-peter-sutcliffe-victims-15169608
https://www.amazon.com/Serial-Killers-Method-Madness-Monsters/dp/0425196402
https://serialkillershop.com/blogs/true-crime/albert-fish
https://www.history.com/this-day-in-history/the-moon-maniac
https://www.refinery29.com/en-us/2019/08/240763/btk-killer-letters-victims-mindhunter-season-2
https://www.amazon.com/American-Serial-Killers-Epidemic-1950-2000/dp/0593198816
https://murderpedia.org/male.R/r/rader-dennis.htm
https://www.youtube.com/watch?v=rcTbPTbochg&t=14s
https://en.wikipedia.org/wiki/Dennis_Rader
https://en.wikipedia.org/wiki/Dennis_Nilsen