1.2.1 Normative References

[W3C-WCAG21-20180605] World Wide Web Consortium, “Web Content Accessibility Guidelines (WCAG) 2.1”, W3C Recommendation 05 June 2018, https://www.w3.org/TR/2018/REC-WCAG21-20180605/

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, http://www.rfc-editor.org/rfc/rfc2119.txt