%% You should probably cite rfc6721 instead of this I-D.
@techreport{snell-atompub-tombstones-18,
    number =    {draft-snell-atompub-tombstones-18},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-snell-atompub-tombstones/18/},
    author =    {James M. Snell},
    title =     {{The Atom "deleted-entry" Element}},
    pagetotal = 10,
    year =      2012,
    month =     jul,
    day =       20,
    abstract =  {This specification adds mechanisms to the Atom Syndication Format that publishers of Atom Feed and Entry documents can use to explicitly identify Atom entries that have been removed. {[}STANDARDS-TRACK{]}},
}