2manyb0x

I saw the "credits to everyone blahblah" text but I'm afraid it's about as useful as posting a video you don't own on youtube and saying something along the lines of "I don't own this video, please don't take it down" in the description. If you're going to do this kind of work professionally, you'll eventually run into trouble if you don't have actual permission to use your sources.
If you're having trouble finding the originals, I recommend you to try out Tineye. It's a very handy way to find out where an image came from.

Since you're not trying to sell any of them, I won't tell a soul, though.

Do notice I do put "Credits to all original stocks." as it is nearly impossible to trace back to the original stocks as there are so much replicates in the internet i.e. through tumblr, pixiv and more. I'm crediting my use of image universally instead of running around claiming the original art as mine ;].



But thanks for the advice.