Toy Story And Monsters Inc Connection- Bonnie Knows Boo-Pixar Theory

Boo from Monsters, Inc. is also Violet from The Incredibles [Spoilers] : r/FanTheories

In Toy Story 3, one of the girls at the Sunnyside Daycare is a slightly older Boo from Monsters, Inc.

Boo from Monsters, Inc makes a cameo in Toy Story 4 - Look to the right of Bonnie in the background! : r/Pixar

1001plus: Coming Out of the Closet

Interview with Mary Gibbs - Boo from Monsters Inc - The Mouselets

Easter Eggs from 'Elemental' and 'Lightyear' That Pixar Fans Are Going to Love

Monsters, Inc.

Monsters Inc: See the Voices Behind Your Favorite Characters

Toy Story 3, Disney Fanon Wiki

Monsters, Inc. : John Goodman, Billy Crystal, James Coburn, Steve Buscemi, Mary Gibbs, Bob Peterson, Jennifer Tilly, Bonnie Hunt, Frank Oz, John Ratzenberger, Daniel R. Gerson, Jeff Pidgeon, Sam Penguin Black