%% You should probably cite rfc3864 instead of this I-D.
@techreport{klyne-msghdr-registry-07,
    number =    {draft-klyne-msghdr-registry-07},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-klyne-msghdr-registry/07/},
    author =    {Graham Klyne and Mark Nottingham and Jeffrey Mogul},
    title =     {{Registration Procedures for Message Header Fields}},
    pagetotal = 17,
    year =      2003,
    month =     oct,
    day =       28,
    abstract =  {This specification defines registration procedures for the message header fields used by Internet mail, HTTP, Netnews and other applications. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.},
}