%% You should probably cite rfc8781 instead of this I-D.
@techreport{ietf-6man-ra-pref64-04,
    number =    {draft-ietf-6man-ra-pref64-04},
    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-6man-ra-pref64/04/},
    author =    {Lorenzo Colitti and Jen Linkova},
    title =     {{Discovering PREF64 in Router Advertisements}},
    pagetotal = 11,
    year =      2019,
    month =     aug,
    day =       12,
    abstract =  {This document specifies a Router Advertisement option to communicate NAT64 prefixes to clients.},
}