Lots of Secret Codes

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

Jason Fung Unisex The Obesity Code: Unlocking The Secrets Of Weight Loss By Dr. - Non Fiction - Paperback

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

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

The Cryptoclub : Using Mathematics to Make and Break Secret Codes

A Pattern of Secrets

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

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)

Spy Science: 40 Secret-Sleuthing, Code-Cracking... - Jim Wiese - Good - Paper...

Codes and Ciphers by Steven Goodwin Paperback

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

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

Deadly Code

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

Codebreaking Sisters: The Sunday Times Bestseller: Our Secret Wa

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

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

Bletchley Park Puzzles and Brainteasers: Could YOU be a top secret codebreaker? (Children's Edition)

The Golden Code

The Mammoth Book of Secret Code Puzzles (Mammoth Books) By Elonka Dunin

Cracking Codes and Cryptograms For Dummies - 0470591005, Sutherland, paperback