%% You should probably cite draft-ietf-calext-serverside-subscriptions instead of this I-D.
@techreport{douglass-serverside-subscriptions-00,
    number =    {draft-douglass-serverside-subscriptions-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-douglass-serverside-subscriptions/00/},
    author =    {Michael Douglass},
    title =     {{Serverside Subscriptions}},
    pagetotal = 10,
    year =      2018,
    month =     sep,
    day =       4,
    abstract =  {This specification provides a mechanism whereby subscriptions to external resources can be handled by the server. This specification updates {[}RFC4791{]} to add new properies for the MKCOL request.},
}