Leopard Big Cat Art and Artists Reference Photos

Here's a preview of a leopard ACEO I've recently done, soon to be auctioned on eBay. No, I don't have a leopard of my own to draw and I didn't take a photo/sketches of one at the zoo to work from. And, I simply cannot use any photo I find on the net or published on paper without permission. (This would be a breach of copyright.) There are a number of websites that provide reference photos for artists to use for free. There are over thirty of them searched in the Find Free to Use Images search engine. One other option is to ask the photographer's permission as I did with Rufus. Today I spotted this list of free stock photography on All Graphic Design & Graphics News. If you scroll to the bottom of that post, you'll see there's also some useful websites listed there.