Gr 4-7--These cryptography titles look at various types of codes, such as Civil War Union Route codes and Navajo code talkers, as well as ingenious deciphering methods. Spoken codes in history, including the Underground Railroad and POWs during the Vietnam War, are introduced by using various examples of word substitutions. Educators will appreciate the concise information provided by codes that have shaped world history. Sample cryptographs are scattered throughout the pages, along with other noteworthy facts. Historical photographs, highlighted vocabulary words and definitions, and do-it-yourself suggestions will keep readers interested. Fans of adventure fiction, such as the popular "39 Clues" series (Scholastic) and Pseudonymous Bosch's "Secret Series" (Little, Brown), will sharpen their super-sleuthing skills in no time. These books are great for beginners of cryptology and those who might be interested in designing a science-fair project display, and they will enhance collections that are weak in this fascinating subject area.--Krista Welz, North Bergen Public Library, NJ[Page 122]. (c) Copyright 2010. Library Journals LLC, a wholly owned subsidiary of Media Source, Inc. No redistribution permitted.