網址: https://static.vecteezy.com/system/resources/previews/021/664/120/original/down-and-up-stair-exit-sign-board-on-green-colored-for-emergency-icon-in-illustration-vector.jpg
網址2: https://www.vecteezy.com/vector-art/21664120-down-and-up-stair-exit-sign-board-on-green-colored-for-emergency-icon-in-vector-illustration
