The Horten Ho IX- Is it the Go229 or the Ho229?

There are people who call the Nurflugel “Horten Go 229” (as said in the kit from Revell, My tank is fight etc) and “Horten Ho 229” (Jet pojects of the 3 reich, DML kit, etc) which is it?

HoIX at smithsonian garber facility

Ho VII

You might want to look at this topic:

http://www.ww2incolor.com/forum/showthread.php?t=5204