1. India Today News.
http://indiatoday.intoday.in/story/ryan-murder-case-16-year-old-cbi-suspect-investigation/1/1087211.html
2. Wikipedia, the Free Encyclopedia.
https://en.wikipedia.org/wiki/2012_Delhi_gang_rape
3. Outlook, the Fully Loaded Magazine.
https://www.outlookindia.com/magazine/story/devil-in-the-flesh/233671
4. The Independent News.
https://www.independent.co.uk/news/long_reads/serial-killers-shipman-brady-hindley-berkowitz-sutcliffe-dennehy-ted-bundy-a8021181.html
5. Glenn, L.A., Raine, A.: Psychopathy and instrumental aggression: evolutionary, neurobiological, and legal perspectives. Int. J. Law Psychiatry 32, 253–258 (2009)