It depends on the license terms,

來源: 於 2012-12-24 12:57:43 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

many did not have any. More do now.

For those who do have license terms now, many need attribution. I am adding them. You can click on the images in this post to see the sources.