1. Abrami PC, Barrett H (2005) Directions for research and development on electronic portfolios. Can J Learn Technol 31(3):1–15
2. Chen-Wilson L (2010) The eCert project. 2010 [cited 2010;
http://ecert.ecs.soton.ac.uk/
]
3. CHESICC (2005) The certificate information verification services in China.
http://www.chsi.com.cn/about_en/
Accessed 02 Sept 2008
4. Davis J (2009) Digital signatures application guidelines on digital signature practices for common criteria security, in MSDN Magazine
5. Digitary (2008) Secure electronic documents.
http://www.digitary.net/aboutus.htm
Accessed 12 Aug 2008