%% You should probably cite rfc6562 instead of this I-D.
@techreport{ietf-avtcore-srtp-vbr-audio-04,
    number =    {draft-ietf-avtcore-srtp-vbr-audio-04},
    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-srtp-vbr-audio/04/},
    author =    {Colin Perkins and Jean-Marc Valin},
    title =     {{Guidelines for the Use of Variable Bit Rate Audio with Secure RTP}},
    pagetotal = 6,
    year =      2011,
    month =     dec,
    day =       30,
    abstract =  {This memo discusses potential security issues that arise when using variable bit rate (VBR) audio with the secure RTP profile. Guidelines to mitigate these issues are suggested. {[}STANDARDS-TRACK{]}},
}