https://en.wikipedia.org/wiki/Vasily_Zaitsev_(sniper)
https://en.wikipedia.org/wiki/Battle_of_Stalingrad
https://en.wikipedia.org/wiki/Operation_Barbarossa
http://www.atchuup.com/vasily-zaytsev-nazi-killing-machine/
https://allthatsinteresting.com/vasily-zaytsev
https://allthatsinteresting.com/ivan-sidorenko