%% You should probably cite rfc8458 instead of this I-D.
@techreport{hakala-urn-nbn-rfc3188bis-00,
    number =    {draft-hakala-urn-nbn-rfc3188bis-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-hakala-urn-nbn-rfc3188bis/00/},
    author =    {Juna Hakala},
    title =     {{Using National Bibliography Numbers as Uniform Resource Names}},
    pagetotal = 21,
    year =      2018,
    month =     apr,
    day =       16,
    abstract =  {National Bibliography Numbers, NBNs, are used by the national libraries and other organizations in order to identify resources in their collections. Generally, NBNs are applied to resources that are not catered for by established (standard) identifier systems such as ISBN. A URN (Uniform Resource Names) namespace for NBNs was established in 2001 in RFC 3188. Since then, several European national libraries have implemented URN:NBN-based systems. This document replaces RFC 3188 and defines how NBNs can be supported within the updated URN framework. A revised namespace registration (version 4) compliant to RFC 8141 is included.},
}