%% You should probably cite draft-ietf-calext-eventpub-extensions instead of this I-D.
@techreport{douglass-calendar-extension-02,
    number =    {draft-douglass-calendar-extension-02},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-douglass-calendar-extension/02/},
    author =    {Mike Douglass},
    title =     {{Event Publishing Extensions to Icalendar}},
    pagetotal = 21,
    year =      2012,
    month =     nov,
    day =       16,
    abstract =  {This specification introduces a number of new iCalendar properties which are of particular use for event publishers and in social networking.},
}