Read Dipper and Mabel's Guide from the story Gravity Falls Secrets by GravityFalls-Decoder (Wild Cipher) with reads.
List of cryptograms - Gravity Falls Wiki - Wikia
17 Gravity Falls GIFs To Brighten Up Your Day - Gnome Puking Rainbow. >>> this was the gift that got me into gravity falls!
Gravity Falls Ciphers with the answers.