- RFC4634
- US Secure Hash Algorithms (SHA and HMAC-SHA). D. Eastlake 3rd; T. Hansen. IETF. July 2006. Informational. URL: https://www.rfc-editor.org/rfc/rfc4634
- RFC5234
- Augmented BNF for Syntax Specifications: ABNF. D. Crocker, Ed.; P. Overell. IETF. January 2008. Internet Standard. URL: https://www.rfc-editor.org/rfc/rfc5234