%% You should probably cite rfc7600 instead of this I-D.
@techreport{ietf-softwire-4rd-09,
    number =    {draft-ietf-softwire-4rd-09},
    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-softwire-4rd/09/},
    author =    {Rémi Després and Sheng Jiang and Reinaldo Penno and Yiu Lee and Gang Chen and Maoke Chen},
    title =     {{IPv4 Residual Deployment via IPv6 - a Stateless Solution (4rd)}},
    pagetotal = 40,
    year =      2014,
    month =     oct,
    day =       13,
    abstract =  {For service providers to progressively deploy IPv6-only network domains while still offering IPv4 service to customers, this document specifies a stateless solution. Its distinctive property is that TCP/UDP IPv4 packets are valid TCP/UDP IPv6 packets during domain traversal, and that IPv4 fragmentation rules are fully preserved end- to-end. Each customer can be assigned one public IPv4 address, or several, or a shared address with a restricted port set.},
}