* HTML5, CSS, JavaScript and XML tutorials: - https://www.w3schools.com/ - https://developer.mozilla.org/en-US/docs/Web * XHTML5 (polyglot markup) usage: - https://wiki.whatwg.org/wiki/HTML_vs._XHTML - http://xmlplease.com/xhtml/xhtml5polyglot/ * Django API reference for templates: - https://docs.djangoproject.com/en/2.0/ref/templates/ * Unicode data support: - https://stackoverflow.com/questions/38363566/trouble-with-utf-8-characters-what-i-see-is-not-what-i-stored * <meta> element usage: - https://moz.com/blog/seo-meta-tags * Linkage to external style sheets or script files via the jsDelivr CDN: - https://www.jsdelivr.com/ * <label> element usage: - https://stackoverflow.com/questions/7636502/why-use-label * Minimum length constraint for <input> elements: - https://stackoverflow.com/questions/10281962/is-there-a-minlength-validation-attribute-in-html5