%% You should probably cite rfc3874 instead of this I-D.
@techreport{ietf-pkix-sha224-01,
    number =    {draft-ietf-pkix-sha224-01},
    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-pkix-sha224/01/},
    author =    {Russ Housley},
    title =     {{A 224-bit One-way Hash Function: SHA-224}},
    pagetotal = 6,
    year =      2004,
    month =     mar,
    day =       31,
    abstract =  {This document specifies a 224-bit one-way hash function, called SHA-224. SHA-224 is based on SHA-256, but it uses a different initial value and the result is truncated to 224 bits. This memo provides information for the Internet community.},
}