%% You should probably cite rfc7641 instead of this I-D.
@techreport{ietf-core-observe-04,
    number =    {draft-ietf-core-observe-04},
    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-core-observe/04/},
    author =    {Klaus Hartke},
    title =     {{Observing Resources in CoAP}},
    pagetotal = 25,
    year =      ,
    month =     ,
    day =       ,
    abstract =  {CoAP is a RESTful application protocol for constrained nodes and networks. The state of a resource on a CoAP server can change over time. This document specifies a simple protocol extension for CoAP that gives clients the ability to observe such changes.},
}