Sonic the Hedgehog CD (Sega CD) - The Cutting Room Floor

Sonic the Hedgehog CD (2011) - The Cutting Room Floor

Sonic the Hedgehog CD (Sega CD) - The Cutting Room Floor

Sonic' Creator Alludes to Michael Jackson Working on 'Sonic 3' Music

Sonic the Hedgehog (2013) - The Cutting Room Floor

Sonic The Hedgehog Sega Genesis Cartridge Magnet

Sonic the Hedgehog CD (2011) - The Cutting Room Floor

Early Sonic 3 prototype found, features major differences to the final game

Sonic CD's Mysterious Cut R2 Level Discussion - Post Origins Edition, Page 32

Sonic the Hedgehog 2 (2013), Sonic Wiki Zone

Sonic the Hedgehog 2 (September 18th, 1992 Beta 4 Prototype) : Free Borrow & Streaming : Internet Archive

Sonic the Hedgehog CD (Sega CD) - The Cutting Room Floor

Sonic & Knuckles Collection - The Cutting Room Floor