GitHub - gatanaso/multiselect-combo-box: A multi select combo box web component based on Polymer and the vaadin-combo-box
Combobox Widget Party: Webix way
Listboxes vs. Dropdown Lists
Multi-Combo Box | SAP Fiori for Web Design Guidelines
GitHub - RWS/Multiselect-ComboBox: The multi selection combo box is a WPF custom control with multiple item selection capabilities, along with customizable features to group, sort and filter items in the collection.
Multiselect Combobox in WPF - CodeProject
c# - How to have multiple selection of items on combobox - Stack Overflow
Issue with multiselect combobox control in Windows 8 - Stack Overflow
Multiselect Combobox (Windows Custom Control) simulates a ComboBox with a CheckedListBox as a Dropdown - CodeProject
Multi-Combo Box | SAP Fiori for Web Design Guidelines
entity framework - Unable to save using Multiselect Item within ComboBox WPF - Stack Overflow
codeigniter - html combo box or select box for multiple selection - Stack Overflow
How to create multi select dropdown - Esri Community