Sources

http://lostinasupermarket.com/2010/02/russian-prison-tattoos/

http://www.phaseloop.com/foreignprisoners/exp-russian_tats.html

http://info.publicintelligence.net/CBSA-TattooHandbook.pdf

http://gangtattoos.blogspot.co.uk/p/russian-mafia.html

http://gangtattoos.blogspot.co.uk/p/mexican-mafia.html

http://publicintelligence.net/ules-mexican-gang-tattoos-identification-guide/

http://mafialifeblog.com/gang-tattoos-their-meaning-and-the-gangs-who-represent-them/