%% You should probably cite draft-ietf-calext-rscale instead of this I-D.
@techreport{daboo-icalendar-rscale-00,
    number =    {draft-daboo-icalendar-rscale-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-daboo-icalendar-rscale/00/},
    author =    {Cyrus Daboo and Gregory Yakushev},
    title =     {{Non-Gregorian Recurrence Rules in iCalendar}},
    pagetotal = 11,
    year =      2013,
    month =     apr,
    day =       26,
    abstract =  {This document defines how non-Gregorian recurrence rules can be specified in iCalendar data.},
}