Gus Grissom - NASA History: Detailed biography of Apollo I Crew member by Mary C. Zornio.
Gus Grissom didn't sink the Liberty Bell 7 Mercury capsule: Space.com article about the American astronaut.
Virgil Ivan “Gus” Grissom: Brief biography from Fact Monster.
Wikipedia - Gus Grissom: Article covers background, career, awards and tributes.