%% You should probably cite rfc7273 instead of this I-D.
@techreport{ietf-avtcore-clksrc-11,
    number =    {draft-ietf-avtcore-clksrc-11},
    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-avtcore-clksrc/11/},
    author =    {Aidan Williams and Kevin Gross and Ray van Brandenburg and Hans Stokking},
    title =     {{RTP Clock Source Signalling}},
    pagetotal = 30,
    year =      2014,
    month =     mar,
    day =       24,
    abstract =  {NTP format timestamps are used by several RTP protocols for synchronisation and statistical measurements. This memo specifies Session Description Protocol (SDP) signalling that identifies timestamp reference clock sources and SDP signalling that identifies the media clock sources in a multimedia session.},
}