https://www.lemon64.com/game/ik-plus
https://archive.org/details/commodore-user-magazine-50/page/n25/mode/2up?view=theater
https://archive.org/details/74-your-commodore-magazine/page/n52/mode/2up?view=theater
http://www.zzap64.co.uk/cgi-bin/displaypage.pl?issue=31&page=12
https://www.c64-wiki.com/wiki/IK%2B