%% You should probably cite draft-campbell-oauth-mtls instead of this I-D.
@techreport{campbell-oauth-tls-client-auth-00,
    number =    {draft-campbell-oauth-tls-client-auth-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-campbell-oauth-tls-client-auth/00/},
    author =    {Brian Campbell and John Bradley},
    title =     {{Mutual X.509 Transport Layer Security (TLS) Authentication for OAuth Clients}},
    pagetotal = 5,
    year =      2016,
    month =     oct,
    day =       10,
    abstract =  {This document describes X.509 certificates as OAuth client credentials using Transport Layer Security (TLS) mutual authentication as a mechanism for client authentication to the authorization server's token endpoint.},
}