Top secret!
Children's 9-12
Ciphers
Business writing
Detectives
Children: Grades 4-6
General
Juvenile literature
An illustrated explanation of twenty-eight secret codes that can be used to send messages.
Borrow to read
This scan is available through Internet Archive's free lending library — sign in or create a free account below, then borrow to read.
Reader not loading? Open it on Archive.org instead.