https://www.scribd.com/search?content_type=documents&page=1&query=john%20altinger&content_types=tops,books,documents&language=1
Britain's Most Evil Killers Season 3, Episode 5 : David Heiss
https://www.telegraph.co.uk/news/uknews/law-and-order/5307573/German-officer-worker-David-Heiss-guilty-of-murdering-student-Matthew-Pyke.html
https://web.archive.org/web/20081209021028/http://warscentral.com/tributepage.shtml
https://www.dailymail.co.uk/news/article-1175100/Pictured-time-The-girlfriend-internet-gamer-stabbed-death-German-love-rival.html
https://www.dailymail.co.uk/news/article-1177555/Student-stabbed-death-German-love-rival-wrote-killers-blood-alert-police.html
http://news.bbc.co.uk/1/hi/england/8040178.stm
https://www.thetimes.co.uk/article/cyber-gamer-david-heiss-fell-for-girl-on-website-then-killed-her-boyfriend-3ddh7mg6v2d
https://www.thetimes.co.uk/article/german-war-gamer-extradited-over-killing-after-online-feud-l8lg5mxl5jn
https://www.reuters.com/article/us-britain-webmurder-life/germans-web-obsession-led-to-savage-british-murder-idUSTRE54A3Z620090511
https://metro.co.uk/2009/05/11/obsessed-gamer-jailed-for-ferocious-murder-of-love-rival-100925/
https://medium.com/the-criminalist/matthew-pyke-wrote-his-killers-name-in-blood-9e9f84c87eb
https://www.watchseries.cyou/tv-series/britains-most-evil-killers-season-3-episode-5/
https://www.postandcourier.com/columbia/faye-swetliks-killer-masked-smells-in-home-acted-strangely-as-new-case-details-revealed/article_bde2a8fa-d913-11eb-9331-f30fd1a7a5d9.html
https://www.youtube.com/watch?v=loVbyxI2LdE