@misc{rfc3967,
    series =    {Request for Comments},
    number =    3967,
    howpublished =  {RFC 3967},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC3967},
    url =       {https://www.rfc-editor.org/info/rfc3967},
    author =    {Dr. Thomas Narten and Randy Bush},
    title =     {{Clarifying when Standards Track Documents may Refer Normatively to Documents at a Lower Level}},
    pagetotal = 6,
    year =      2005,
    month =     jan,
    abstract =  {IETF procedures generally require that a standards track RFC may not have a normative reference to another standards track document at a lower maturity level or to a non standards track specification (other than specifications from other standards bodies). For example, a standards track document may not have a normative reference to an informational RFC. Exceptions to this rule are sometimes needed as the IETF uses informational RFCs to describe non-IETF standards or IETF-specific modes of use of such standards. This document clarifies and updates the procedure used in these circumstances. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.},
}