https://www.wearethemighty.com/gear-tech/how-50-cal-kills-you?rebelltitem=2#rebelltitem2
https://www.snipercountry.com/338-lapua-vs-50-bmg/
http://pwencycl.kgbudge.com/2/0/20mm_Oerlikon_AA_gun.htm
http://www.navweaps.com/Weapons/WNBR_2cm-85_GAM.php
https://web.archive.org/web/20141109220010/http://www.quarryhs.co.uk/ammotable2.htm
https://fas.org/man/dod-101/sys/land/slap.htm
https://www.google.com/books/edition/M1_Abrams_vs_T_72_Ural/w9bvCwAAQBAJ?hl=en&gbpv=1&printsec=frontcover
https://www.aircav.com/cobra/ammo20.html
https://safelifedefense.com/body-armor-guide/#tab-con-13
https://www.techeblog.com/anzio-20mm-just-might-be-worlds-largest-sniper-rifle-this-video-shows-someone-firing-it/
https://www.americanrifleman.org/articles/2017/2/23/the-50-cal-browning-machine-gun-the-gun-that-won-the-war/
https://fas.org/man/dod-101/sys/land/50.htm
https://web.archive.org/web/20090320043840/http://www.accuratepowder.com/data/AccurateGuideV3-2.pdf
https://www.gd-ots.com/wp-content/uploads/2017/11/20mm-MK149.pdf
https://apps.dtic.mil/dtic/tr/fulltext/u2/024953.pdf