ITU-T Recommendation X.509(2000) ISO/IEC 9594-8: 2001: Information Technology Open Systems Interconnection The Di-rectory: Public-key and Attribute Certificate Framework (2000).
Housley, R., Polk, T., Ford, W. and Solo, D.: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile, RFC 3280, IETF (Apr.2002).