%% You should probably cite rfc7647 instead of this I-D.
@techreport{ietf-sipcore-refer-clarifications-04,
    number =    {draft-ietf-sipcore-refer-clarifications-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-sipcore-refer-clarifications/04/},
    author =    {Robert Sparks and Adam Roach},
    title =     {{Clarifications for the Use of REFER with RFC 6665}},
    pagetotal = 6,
    year =      2015,
    month =     apr,
    day =       22,
    abstract =  {The SIP REFER method relies on the SIP-Specific Event Notification framework. That framework was revised by RFC 6665. This document highlights the implications of the requirement changes in RFC 6665, and updates the definition of the REFER method described in RFC 3515 to clarify and disambiguate the impact of those changes.},
}