สร้าง Drop Down List ใน Excel ไม่ยากอย่างที่คิด

https://ezoffice.wordpress.com/2011/08/04/%E0%B8%AA%E0%B8%A3%E0%B9%89%E0%B8%B2%E0%B8%87-drop-down-list-%E0%B9%83%E0%B8%99-excel-%E0%B9%84%E0%B8%A1%E0%B9%88%E0%B8%A2%E0%B8%B2%E0%B8%81%E0%B8%AD%E0%B8%A2%E0%B9%88%E0%B8%B2%E0%B8%87%E0%B8%97/