If the exact image you are using cannot be found in their own publishings (some are print-exclusives that you may not have personally obtained), you must be able to show a clear relationship between the artists works, and the image you’re using as your source (it’s pretty easy to see that it was the same artist, for example, when you place two Sakizou illustrations side-by-side, cosplay costumes for men due to distinct art style) “I found this on tumblr/pixv/pinterest/art-share account” is NOT an acceptable source.
