This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
ListcoloringK.svg list coloring problem on the complete bipartite graph is at least four own David Eppstein Graph coloring vertex Files by User David Eppstein from en Cczero
Page 2023 Free-images.com. All images are Public Domain