%% You should probably cite draft-saintandre-vcarddav-thing instead of this I-D.
@techreport{saintandre-vcard-thing-00,
    number =    {draft-saintandre-vcard-thing-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-saintandre-vcard-thing/00/},
    author =    {Peter Saint-Andre},
    title =     {{vCard KIND:thing}},
    pagetotal = 4,
    year =      2011,
    month =     apr,
    day =       6,
    abstract =  {This document defines a vCard entity kind of "thing".},
}