Lots of Secret Codes

Sensational Snow Day Puzzles for Kids : Chill Out with Frosty Facts, Secret Codes, Challenging Mazes, and Lots of Surprises!

The Obesity Code: unlocking the secrets of weight loss-Jason Fung

Secret Code Games for Clever Kids®: More than 100 secret agent and spy puzzles to boost your brainpower

The Ultimate Code Breaker's Puzzle Book : Over 50 Puzzles to become a super spy, crack codes and train your brain

A Pattern of Secrets

Survival Codes

brainPLAY Top Secret Spy Puzzles and Codes: Puzzle Book Packed with Brain Teasers and Hidden Pictures Challenges for Kids 7 and Up (brainPLAY Puzzle Books)

Codeword Puzzle Books for Adults: 100+ Puzzles for Adults and Teens, Large Print Codeword Puzzle Book for Adults, Codewords

200 Codeword puzzle book for adults: code breaker book for adults, teens and seniors

The Code Book: The Secret History of Codes and Code-breaking by Simon Singh Book

Introduction to Codes and Ciphers: Plus 20 Famous Unsolved Codes, Ciphers, and Mysterious Writings. Can You Solve Them?

The Ultimate CODE WORD Book 1: Volume 1 (200 Cleverly Crafted Codeword Puzzles)

Codebreaking Sisters: The Sunday Times Bestseller: Our Secret Wa

Murdle Junior Mysteries: Codes, Cover-ups and Cookies: A Mystery Novel

The Ultimate CODE WORD Book 2: Volume 2 (200 Cleverly Crafted Codeword Puzzles)

Cracking the Communication Code

Big Book of Codewords Book 1 : a bumper codeword book for adults containing 300 puzzles

Extra Large Print Codewords: 100 easy to read codeword puzzles for adults

190 Codewords Puzzle Book For Adults (Vol 02): Large Print Codeword Books For Adults, Teens, Seniors, and More!

SPIED: Can YOU Crack the Code as a Secret Agent? (Click Your Poison)

Big Codeword Book: 300+ Easy, Medium and Hard Puzzles for Adults

The Squishmallow Code: A Thrilling Adventure Mystery for Kids 9-12 – Action-Packed, Fast-Paced Fiction with Hidden Clues, Secret Codes, and a Race to Unlock a Legendary World!