%% You should probably cite draft-ietf-httpbis-client-cert-field instead of this I-D.
@techreport{bdc-something-something-certificate-05,
    number =    {draft-bdc-something-something-certificate-05},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-bdc-something-something-certificate/05/},
    author =    {Brian Campbell},
    title =     {{Client-Cert HTTP Header: Conveying Client Certificate Information from TLS Terminating Reverse Proxies to Origin Server Applications}},
    pagetotal = 13,
    year =      2021,
    month =     mar,
    day =       23,
    abstract =  {This document defines the HTTP header field "Client-Cert" that allows a TLS terminating reverse proxy to convey the client certificate of a mutually-authenticated TLS connection to the origin server in a common and predictable manner.},
}