SC Cheats & Glitches: Sonic 3 & Knuckles - Debug & Level Select

Sonic the Hedgehog 2's Biggest Easter Egg and Other References - IGN

Video game cheating: A brief history

Sonic 3 & Knuckles (Video Game) - TV Tropes

Tails' Channel, celebrating 15 years on X: A number of Sonic 3 & Knuckles soundtest features were added in the latest update. @TheOcelot01 recapped all the codes in the list below. #SonicNews

Sonic the Hedgehog 3 (prototype; 1993-11-03)/Hidden content - Sonic Retro

All Sonic Origins Cheat Codes: Level Select, Debug and More - Prima Games

Hacks - Sonic 1 Megamix

Sonic Origins 1.04 (Switch's 1.4.0) update released, addresses almost 50 bugs.

Sonic & Knuckles Collection - PCGamingWiki PCGW - bugs, fixes

Sonic Origins level select codes and how to find Hidden Palace