%% You should probably cite rfc8262 instead of this I-D.
@techreport{ietf-sipcore-content-id-01,
    number =    {draft-ietf-sipcore-content-id-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-sipcore-content-id/01/},
    author =    {Christer Holmberg and Ivo Sedlacek},
    title =     {{Content ID header field in Session Initiation Protocol (SIP)}},
    pagetotal = 8,
    year =      2017,
    month =     mar,
    day =       8,
    abstract =  {This document specifies the Content-ID header field for usage in the Session Initiation Protocol (SIP).},
}