https://www.census.gov/programs-surveys/decennial-census.html
http://www.justicedenied.org/billheir.htm
http://law-forensic.com/cfr_heirens_2.htm
https://murderpedia.org/male.H/h/heirens-william.htm
https://allthatsinteresting.com/william-heirens-lipstick-killer
https://www.chicagotribune.com/news/breaking/chi-william-heirens-dies-known-as-the-lipstick-killer-20120306-story.html
https://www.nytimes.com/2012/03/07/us/william-heirens-the-lipstick-killer-dies-at-83.html
https://www.dnainfo.com/chicago/20160107/edgewater/70-years-after-lipstick-murders-doubt-over-killers-guilt-still-lingers
https://www.gq.com/story/william-heirens-lipstick-killer-chicago
https://www.thefamouspeople.com/profiles/william-heirens-35503.php
http://www.justicedenied.org/billheir.htm
https://www.gq.com/story/william-heirens-lipstick-killer-chicago#:~:text=The%20blood%2Dsplattered%20apartment%20had,at%20the%20Pine%20Grove%20Hotel.
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=960125