Codes & Secret Writing by Herbert S. Zim, 4th Scholastic paperback printing, TX164, 1962, 116 pages. Illustrated by the author. Authorized Abridgement.
DESCRIPTION:“Looking for fun? Want to mystify everybody you know? Do you need to send really private messages? Here’s just the book for you. Easy-to-follow, step-by-step explanations of how secret codes can be made. You can practice both encoding and decoding. You’ll even learn to work out a code of your own that will fool many a code expert.
You’ll have fun learning about position codes- code wheels, secret languages, reverse codes- and many more. Best of all, there are two entire chapters on secret writing and invisible inks.” (from the back cover)