%% You should probably cite rfc9211 instead of this I-D.
@techreport{ietf-httpbis-cache-header-00,
    number =    {draft-ietf-httpbis-cache-header-00},
    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-httpbis-cache-header/00/},
    author =    {Mark Nottingham},
    title =     {{The Cache HTTP Response Header}},
    pagetotal = 7,
    year =      2019,
    month =     jan,
    day =       28,
    abstract =  {To aid debugging, HTTP caches often append headers to a response detailing how they handled the request. This specification codifies that practice and updates it for HTTP's current caching model.},
}