Winokur, Eric. Secret codes / [electronic resource] / by Eric Winokur.. New York : : Trumpet Club,, c1990.. 58 p. ; 20 cm. + decoder disk. (Explorer books).



ISBN: 0440841542 9780440841548

Subjects--Topical Terms:
Cryptography.
Ciphers.
Cryptography.
Ciphers.