SEGA - This is Sonic the Hedgehog, born 23 years ago in 1991. We

Evolution of SONIC THE HEDGEHOG - 31 Years Explained

Sonic The Hedgehog (Sega Genesis) - This Day in Gaming History - 6/23/1991

The Making of Sonic the Hedgehog and a Chat With World-Renown Video Game Designer Hirokazu Yasuhara

Is Sonic the Hedgehog still popular in the United States? - Quora

Sonic Superstars - Wikipedia

The History of Sonic the Hedgehog: The Genesis Era - LevelSkip

Happy Birthday, Sonic the Hedgehog? - Sonic Retro

Daily Operation: Sega Releases Sonic the Hedgehog (June 23, 1991)

TIME for Kids