Gravity Falls' Alex Hirsch Explains Plans for Dipper and Mabel's 13th Birthday

Gravity Falls creator Alex Hirsch can

Gravity Falls: Dipper's and Mabel's Guide to Mystery and Nonstop Fun! by Rob Renzetti

Dipper and Mabel vs. the Future, Gravity Falls Wiki

Dipper Pines, Regular Show Fanon Wiki

Dipper Pines, Gravity Falls Wiki

The Truth About Possessed Dipper Explained - GravityFalls #gravityfall

Alex Hirsch on the Origins of The Zodiac

The Final Countdown: Number 1: Gravity Falls: “Dipper and Mabel vs. The Future”/”Weirdmageddon Parts 1 and 2” – yahoo201027

Dipper and Mabel vs. the Future, Gravity Falls Wiki

Alex Hirsch's inspiration for Dipper and Mabel vs. the Future