1. M. Abadi, N. Glew, B. Horne, and B. Pinkas .Certified email with a light on-line trusted third party: Design and implementation .Proceedings of 2002 International World Wide Web Conference, pages387 -395 ,Honolulu, HI,May2002 .
2. N. Asokan, M. Schunter, and M. Waidner .Optimistic protocols for fair exchange .Proceedings of 1997 ACM Conference on Computer and Communications Security, pages7 -17 ,Zurich, Switzerland,April1997 .
3. N. Asokan, V. Shoup, and M. Waidner .Asynchronous protocols for optimistic fair exchange .Proceedings of 1998 IEEE Symposium on Security and Privacy, pages86 -99 ,Oakland, CA,May1998 .
4. N. Asokan, V. Shoup, and M. Waidner .Optimistic fair exchange of digital signatures. Lecture Notes in Computer Science 1403 ,Proceedings of Eurocrypt '98, pages591 -606 ,Helsinki, Finland,June1998 .
5. G. Ateniese, B. Medeiros, and M. Goodrich .TRICERT: Distributed certified email schemes .Proceedings of 2001 Network and Distributed System Security Symposium,San Diego, CA,February2001 .