Textbook: Introduction to Graph Theory by Robert J. Wilson 5th Edition Pg. 91

4.19 Let Gbe a simple graph with at least 11 vertices, and let G be its complement. (i) Prove that G and G cannot both be planar. (In fact, a similar result holds if 11 is replaced by 9, though this is difficult to prove.) (i) Find a graph G with eight vertices for which G and G are both planar