%% You should probably cite rfc7809 instead of this I-D.
@techreport{ietf-tzdist-caldav-timezone-ref-05,
    number =    {draft-ietf-tzdist-caldav-timezone-ref-05},
    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-tzdist-caldav-timezone-ref/05/},
    author =    {Cyrus Daboo},
    title =     {{Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference}},
    pagetotal = 13,
    year =      2015,
    month =     oct,
    day =       13,
    abstract =  {This document defines an update to the Calendaring Extensions to WebDAV (CalDAV) calendar access protocol (RFC 4791) to allow clients and servers to exchange iCalendar data without the need to send full time zone data.},
}