https://www.nationalgeographic.com/archaeology-and-history/magazine/2016/11-12/sparta-military-greek-civilization/
https://study.com/academy/lesson/daily-life-in-sparta.html
http://www.ancientgreece.co.uk/staff/resources/background/bg1/home.html
https://allthatsinteresting.com/krypteia-sparta
https://en.wikipedia.org/wiki/Agoge