Even if it's not considered canon, Dragon Ball GT's Super Saiyan 4 form is still a memorable and important transformation.
Why Dragon Ball GT's Super Saiyan 4 Actually Matters
Who wins, (DBS) SSJ4 Goku or (GT/Adult) SSJB Goku? - Quora
Super Saiyan 4, Dragon Ball Wiki
Dragon Ball FighterZ: 10 Things You Should Know About SSJ4 Gogeta
dragon ball gt The Nostalgia Spot
Dragon Ball Super Improved GT's Biggest Villain
Dragon Ball GT (Anime) - TV Tropes
re: Gotenks Post Rosat power - Page 8 - Dragon Ball Forum - Neoseeker Forums