16. C. L. Song, Y. L. Wang, Y. P. Jiang, Y. Zhang, C. Z. Chang, L. L. Wang, K. He, X. Chen, J. F. Jia, Y. Y. Wang, Z. Fang, X. Dai, X. C. Xie, X. L. Qi, S. C. Zhang, Q. K. Xue, and X. C. Ma, Topological insulator Bi2Se3 thin films grown on double-layer graphene by molecular beam epitaxy, APPLIED PHYSICS LETTERS 97, 143118 (2010).