Deok-Soo Kim, Hyuksang Kwon, Alexey Yu. Nikitin, Seongjin Ahn, Luis Martin-Moreno, Francisco J. Garcia-Vidal, Sunmin Ryu, Hongki Min, and Zee Hwan Kim, “Stacking Structures of Few-Layer Graphene Revealed by Phase-Sensitive Infrared Nanoscopy”, ACS Nano, 9(7), 6765-6773 (2015).