1. Applied Cryptography: Protocols, Algorithms, and Source Code in C 2nd Edition, by Bruce Schneier Wiley Publishing 1996 ISBN 0-471-11709-9 2. The Computer Privacy Handbook: A Practical Guide to E-Mail Encryption, Data Protection, and PGP Privacy Software by Andre Bacard Peachpit Press 1995 ISBN 1-56609-171-3 $24.95 Reference: http://american-writers.org/