%% You should probably cite rfc2157 instead of this I-D.
@techreport{ietf-mixer-bodymap-06,
    number =    {draft-ietf-mixer-bodymap-06},
    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-mixer-bodymap/06/},
    author =    {Harald T. Alvestrand},
    title =     {{Mapping between X.400 and RFC-822/MIME Message Bodies}},
    pagetotal = 49,
    year =      1996,
    month =     sep,
    day =       2,
    abstract =  {This document defines how to map body parts of X.400 messages into MIME entities and vice versa, including the handling of multipart messages and forwarded messages. {[}STANDARDS-TRACK{]}},
}