Sources

Wikipedia: Walter E. Ellis

https://en.wikipedia.org/wiki/Walter_E._Ellis

Murderpedia: Walter Ellis

https://murderpedia.org/male.E/e/ellis-walter.htm

Wisconsin Serial Killer dies in South Dakota Prison

https://wislawjournal.com/2013/12/02/wisconsin-serial-killer-dies-in-south-dakota/

Serial Killers - Podcast

https://podcasts.apple.com/us/podcast/milwaukee-north-side-strangler-walter-e-ellis/id1205030005?i=1000481748033

Serial Killers of Wisconsin

http://serialkillersofwisconsin.weebly.com/walter-ellis.html