optgroup> - OPTGROUP TAG IN HTML
HTML Select, Option and Optgroup tags - Lena Design
File:HTML-select-optgroup-example-gl.png - Wikimedia Commons
How to specify a label for an optgroup tag in HTML5 ? - GeeksforGeeks
The optgroup in HTML select forms in Dreamweaver - Web Teacher
Using option groups (<OPTGROUP>) in Forms 2.0 picklists — TEKNKL :: Blog
HTML optgroup Tag - HowToCodeSchool.com - YouTube
OPTGROUP Tag in HTML || HTML Optgroup Tag
HTML <optgroup> Tag - GeeksforGeeks
Elemento optgroup en HTML - BigCode
Styling single selection menu control option groups (optgroup elements) with CSS | 456 Berea Street
javascript - How to Dynamically Create <option> elements within a parent < optgroup> - Stack Overflow
HTML <optgroup> Tag
Etiqueta optgroup HTML5: Agrupar las opciones de un select
Styling single selection menu control option groups (optgroup elements) with CSS | 456 Berea Street
HTML optgroup Tag - YouTube
Select2 v4.0 make optgroups selectable - Stack Overflow
javascript - HTML multi select add clickable input checkbox before the optgroup text - Stack Overflow
Styling single selection menu control option groups (optgroup elements) with CSS | 456 Berea Street
HTML optgroup Tag
Quick Tip: Don't Forget the “optgroup” Element
html tutorial - <optgroup> Tag in HTML - html5 - html code - html form - In 30Sec by Microsoft Award MVP - | wikitechy
