關於「Postcard size in cm」標籤，搜尋引擎有相關的訊息討論：

A Guide to Postcard Sizes and Printing - Gold Image Printingwww.goldimageprinting.com › standard-postcard-sizePostcard Size - Dimensions, Inches, mm, cms, Pixel - Template.netwww.template.net › Graphic DesignPostcard Specifications - Postal Serviceswww.post.gov.tw › post › inte